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PLOS One logoLink to PLOS One
. 2023 Oct 26;18(10):e0291316. doi: 10.1371/journal.pone.0291316

Global burden and trends of ectopic pregnancy: An observational trend study from 1990 to 2019

Shufei Zhang 1,#, Jianfeng Liu 1,#, Lian Yang 1, Hanyue Li 1, Jianming Tang 1, Li Hong 1,*
Editor: Gang Qin2
PMCID: PMC10602312  PMID: 37883498

Abstract

Background

Ectopic pregnancy (EP) is one of the leading causes of death in women in early pregnancy, and the mortality of EP have gradually decreased over time in developed countries such as the United Kingdom and the United States. However, epidemiological information on EP has been lacking in recent years, so we analyzed EP data over a thirty-year period from 1990–2019 with the help of Global Burden of Disease study (GBD) data to fill this gap.

Methods

According to the EP data in GBD for the three decades from 1990 to 2019, we used estimated annual percentage changes (EAPC) to assess the trend of age-standardized incidence rate (ASIR), age-standardized death rate (ASDR) and age-standardized disability adjusted life years (AS-DALYs) trends in EP and to explore the correlation between socio-demographic index (SDI) stratification, age stratification and EP.

Results

Global ASIR, ASDR, AS-DALYs for EP in 2019 are 170.33/100,000 persons (95% UI: 133.18 to 218.49), 0.16/100,000 persons (95% UI, 0.14 to 0.19) and 9.69/100,000 persons (95% UI, 8.27 to 11.31), respectively. At the overall level, ASDR is significantly negatively correlated with SDI values (R = -0.699, p < 0.001). Besides that, ASDR and AS-DALYs have basically the same pattern. In addition, iron deficiency is one of the risk factors for EP.

Conclusions

In the past three decades, the morbidity, mortality and disease burden of EP have gradually decreased. It is noteworthy that some economically disadvantaged areas are still experiencing an increase in all indicators, therefore, it is more important to strengthen the protection of women from ethnic minorities and low-income groups.

1. Introduction

Ectopic pregnancy (EP) is the implantation of the gestational sac outside the uterine cavity and its typical clinical manifestations are menopause, abdominal pain, and vaginal bleeding. And EP is a significant cause of maternal morbidity and unexpected death worldwide [1, 2]. Tubal infection resulting from upper genital tract infection is a major cause of EP, and infectious agents like Mycoplasma genitalium and Chlamydia trachomatis are important risk factors.

Developed countries with well-established healthcare systems have relatively reliable epidemiological data. Previous studies have shown an increase in the incidence of EP in countries like the United States, with the rate rising from 4.5 to 9.4 cases per 1000 reported pregnancies between 1970 and 1978 [3]. By 1989, there was a fourfold increase compared to 1970 [4]. Not only this, but other developed countries such as Canada, New Zealand, and the United Kingdom have shown similar increasing trends in the incidence of EP [57]. On the contrary, developing countries, particularly in Africa, have limited epidemiological data on EP, and only a few early studies indicate an increasing trend in EP incidence [8]. A study conducted in China showed that the prevalence of EP was around 2.5% in 2004 and exhibited an overall decreasing trend from 2011 to 2020. However, a change in fertility policy in 2015 resulted in an increase in the proportion of EP among individuals aged 35 years and older [9]. It is worrisome that underdeveloped countries lack comprehensive epidemiological data on EP due to poor medical and economic conditions. Consequently, assessing the prevalence of risk factors such as Chlamydia trachomatis infection and pelvic inflammatory disease is the only way to speculate, making the EP situation in underdeveloped countries less optimistic [10].

Despite a significant decrease in EP mortality in countries like the United Kingdom and the United States at the end of the last century, it remains high in developing countries [1]. The incidence of EP continues to rise, resulting in a substantial disease burden. However, global epidemiological studies of EP are still lacking.

Explore results from the 2019 Global Burden of Disease study (GBD 2019), which published epidemiological data related to 369 diseases/injuries and 286 causes of death, covered EP in 204 countries and territories from 1990 to 2019 [11]. In this context, we analyzed the GBD data from 1990 to 2019, examining various aspects such as incidence, mortality, and risk factors associated with EP, aiming to support the management of EP patients worldwide and inform public health policy development.

2. Materials and methods

2.1 Data acquisition

In GBD, EP is defined as pregnancy occurring outside of the uterus. (https://www.healthdata.org/results/gbd_summaries/2019/ectopic-pregnancy-level-4-cause). Study data was obtained from GBD 2019 was modeled by the Institute for Health Metrics and Evaluation (IHME) [12].

The Socio-demographic Index (SDI) is a composite indicator of development status strongly correlated with health outcomes. It is the geometric mean of 0 to 1 indices of total fertility rate under the age of 25, mean education for those ages 15 and older and lag distributed income per capita. As a composite, a location with an SDI of 0 would have a theoretical minimum level of development relevant to health, while a location with an SDI of 1 would have a theoretical maximum level [13] (https://ghdx.healthdata.org/gbd-2019). SDI data was obtained from Global Health Data Exchange (GHDx).

2.2 Statistical analysis

To evaluate trends in incidence rate, death rate, and burden of EP, we calculated relevant assessment indicators, namely annual age-standardized incidence rate (ASIR), age-standardized mortality rate (ASDR), and age-standardized DALYs rate (AS-DALYs). Not only that, we used annual percentage change (EAPC) to accurately evaluate the trend of ASR [14].

The EAPC is calculated by fitting the linear regression line: Y = α + βx + ε, where y represents ln(ASR) and x refers to the calendar year. The value of EAPC equals 100 × (exp(β) − 1) and its 95% CI is attainable in the regression model [15, 16]. And the ASR was obtained as follows:

ASR=i=1Aaiwii=1Awi×10000

In the ith age subgroup, ai is represented as age class. wi denotes the number of persons (or weight), where i is equal to the selected reference standard population [17]. when both the EAPC value and its 95% CI >0, we consider its ASR to be on an upward trend; when both the EAPC value and 95% CI <0, we consider its ASR to be on an downward trend; In other cases, we consider the ASR to be stable [18]. We use Pearson’s correlation coefficient (R) to represent the strength of the correlation, and all analyses and data visualization are done in R software (version 4.2.1, http://www.r-project.org/, Auckland, New Zealand).

3. Results

3.1 Distribution and trends in the incidence rate of EP

At the global level, there were 6.7 million (95% UI: 5.2 to 8.6) incident cases of EP in 2019, with an ASIR of 170.33/100,000 persons (95% UI: 133.18 to 218.49). The number of cases in 2019 was 0.1% lower than in 1990 (95% UI: -0.16 to -0.04). It is worth drawing our attention to the fact that only the number of incidence cases in the low SDI region increased by 0.53% (95% UI: 0.48 to 0.58) during these three decades (Table 1). On observation from the GBD regions and countries level, the three countries with the highest ASIR are Niger, Papua New Guinea, and Chad; the three countries with the lowest ASIR are Australia, South Africa, and Poland (Fig 1A and S1 Table).

Table 1. Incidence of ectopic pregnancy in 1990 and 2019 for all locations, with EAPC from 1990 and 2019.

Location 1990 2019 1990–2019
Incident cases
No. × 103(95% UI)
ASR per 100,000
No. (95% UI)
Incident cases
No. × 103(95% UI)
ASR per 100,000
No. (95% UI)
Case change
No. (95% UI)
EAPC
No. (95% CI)
Global 7453.3 (5739 to 9557.1) 266.79 (204.3 to 343) 6692.4 (5225.4 to 8598.6) 170.33 (133.18 to 218.49) -0.1% (-0.16 to -0.04) -1.15% (-1.31 to -0.99)
Socio-demographic index
Low 983.2 (765.5 to 1292.7) 418.6 (326.44 to 548.26) 1501.7 (1156.2 to 1982.9) 273.81 (211.25 to 359.81) 0.53% (0.48 to 0.58) -1.47% (-1.57 to -1.38)
Low-middle 1778.5 (1369.1 to 2281.4) 322.26 (249.36 to 413.27) 1512.4 (1160.3 to 1976.9) 158.49 (122.09 to 207.04) -0.15% (-0.19 to -0.09) -2.29% (-2.33 to -2.24)
Middle 2269 (1717.2 to 2955.8) 242.8 (182.99 to 319.2) 1659.3 (1267 to 2189.6) 130.52 (99.99 to 170.65) -0.27% (-0.34 to -0.2) -1.59% (-1.85 to -1.33)
Middle-high 1795.2 (1362.1 to 2341.2) 285.13 (216.49 to 372.19) 1461.7 (1121.1 to 1931.8) 199.34 (153.88 to 260.35) -0.19% (-0.28 to -0.08) -0.31% (-0.69 to 0.08)
High 624.3 (466.7 to 833.9) 144.76 (108.1 to 191.81) 553.2 (434.8 to 705) 119.41 (94.75 to 153.59) -0.11% (-0.22 to 0.01) -0.66% (-0.72 to -0.6)
Region
High-income Asia Pacific 64.2 (46.1 to 88) 74.71 (53.42 to 102.65) 46 (35.3 to 60.6) 61.66 (47.63 to 81.69) -0.28% (-0.38 to -0.14) -0.72% (-0.9 to -0.53)
Central Asia 118.5 (88 to 156.6) 319.83 (239.91 to 420.44) 117.1 (86.8 to 154.9) 230.1 (170.92 to 302.57) -0.01% (-0.07 to 0.06) -0.65% (-0.99 to -0.31)
East Asia 2557 (1898.9 to 3370.1) 356.51 (263.65 to 473.15) 1463 (1108.3 to 1970.1) 192.01 (145.74 to 253.91) -0.43% (-0.51 to -0.34) -0.87% (-1.36 to -0.39)
South Asia 1562.5 (1192.9 to 2072.7) 292.68 (224.78 to 387.73) 1351.9 (992.4 to 1808.8) 136.56 (101.21 to 182.39) -0.13% (-0.19 to -0.06) -2.68% (-2.72 to -2.64)
Southeast Asia 404.4 (307.7 to 534.5) 164.93 (125.99 to 219.09) 377.8 (289 to 506.8) 104.78 (79.97 to 140.16) -0.07% (-0.12 to -0.02) -1.44% (-1.49 to -1.39)
Australasia 9 (6.3 to 13.2) 82.39 (57.81 to 119.74) 9.1 (7.1 to 11.7) 65.74 (51.75 to 84.72) 0.01% (-0.19 to 0.26) -0.6% (-0.95 to -0.25)
Caribbean 34.4 (25.9 to 45.6) 179.56 (135.15 to 238.74) 34.1 (25.6 to 45.8) 140.35 (105.88 to 188.53) -0.01% (-0.08 to 0.07) -0.78% (-0.87 to -0.7)
Central Europe 81.8 (61.8 to 107.3) 143.21 (107.21 to 188.92) 57.7 (44.4 to 74.5) 117.39 (89.64 to 151.53) -0.3% (-0.4 to -0.17) -0.35% (-0.71 to 0.02)
Eastern Europe 360.8 (273.2 to 477) 329.52 (251.34 to 437.56) 350.2 (260.9 to 469.6) 349.96 (262.95 to 457.78) -0.03% (-0.18 to 0.14) 1.44% (0.85 to 2.04)
Western Europe 311.6 (233.2 to 415.3) 160.01 (119.86 to 212.77) 341.3 (259.1 to 444.1) 181.16 (137.85 to 238.2) 0.1% (-0.03 to 0.25) 0.68% (0.58 to 0.79)
Andean Latin America 75.9 (58.5 to 98.6) 404.47 (310.72 to 534.09) 89.5 (68.1 to 117.3) 265.71 (202.64 to 347.58) 0.18% (0.09 to 0.28) -1.26% (-1.4 to -1.13)
Central Latin America 195.8 (145.6 to 264.7) 232.32 (172.32 to 313.57) 207.1 (161.7 to 270.5) 152.73 (119.06 to 199.48) 0.06% (-0.02 to 0.15) -1.88% (-2.05 to -1.71)
Southern Latin America 112.3 (84.5 to 148.4) 448.06 (336.78 to 590.45) 117 (87 to 158.2) 336.75 (250.85 to 450.64) 0.04% (-0.06 to 0.17) -0.83% (-0.93 to -0.73)
Tropical Latin America 99.1 (76.2 to 129.7) 118.85 (91.56 to 155.51) 103.5 (77.7 to 140.5) 85.28 (64.24 to 115.29) 0.04% (-0.04 to 0.13) -0.97% (-1.08 to -0.86)
North Africa and Middle East 389.1 (300.2 to 510.7) 246.28 (190.51 to 324.35) 443.4 (338.2 to 595.1) 134.89 (103.09 to 180.11) 0.14% (0.07 to 0.22) -2.01% (-2.13 to -1.88)
High-income North America 194.7 (137.3 to 269) 127.15 (90.15 to 175.8) 132.5 (111.1 to 162.9) 79.81 (66.99 to 98.02) -0.32% (-0.45 to -0.13) -2.36% (-2.78 to -1.94)
Oceania 13 (9.7 to 17.4) 429.24 (321.55 to 568.66) 25.4 (19 to 33.7) 377.18 (281.64 to 502.22) 0.96% (0.78 to 1.15) -0.46% (-0.47 to -0.44)
Central Sub-Saharan Africa 105.5 (81 to 141.5) 431.16 (326.68 to 572.8) 175.6 (132.1 to 237.7) 282.28 (211.09 to 383.12) 0.66% (0.53 to 0.86) -1.31% (-1.5 to -1.11)
Eastern Sub-Saharan Africa 359.1 (276.4 to 473.6) 423.25 (326.19 to 560.24) 550.5 (421.7 to 735.7) 270.41 (206.59 to 360.42) 0.53% (0.47 to 0.59) -1.57% (-1.65 to -1.49)
Southern Sub-Saharan Africa 35.3 (27.3 to 45.8) 127.56 (98.91 to 165.69) 36 (27.7 to 46.9) 81.41 (62.94 to 105.76) 0.02% (-0.05 to 0.09) -1.49% (-1.6 to -1.39)
Western Sub-Saharan Africa 369.1 (286.3 to 486) 431.56 (334.89 to 570.4) 663.8 (509.5 to 884.7) 299.34 (229.06 to 398.25) 0.8% (0.75 to 0.85) -1.21% (-1.3 to -1.11)

Fig 1.

Fig 1

Distribution of (A) ASIR, (B) ASDR, (C) AS-DALYs and (D) EAPC-ASIR in various countries and regions in 2019.

In the global overall level analysis, incidence rates were lower in 2019 than in 1990 for all age stages, with peak incidence rates occurring in the 25–29 age group. incidence rates were significantly higher in women aged 25–34 years, which also appears to be consistent with a sexually active period for women. incidence rates in 2019 were generally lower than 1990 incidence rates, and interestingly, incidence rates in high SDI regions in the 30+ stage exceeded those in 1990, while incidence rates in high-moderate SDI regions exceeded those in 1990 in the 35+ stage. Not only that, the peak prevalence in each region was largely consistent with the global level, with the prevalence peaking at 25–29 years of age in both 1990 and 2019, while the high SDI region showed a pushed-back peak in 2019 (Fig 2).

Fig 2. Distribution of incidence rate in different SDI regions, age distribution of incidence rate in different SDI regions from 1990–2019.

Fig 2

On observation from the GBD regions and countries level, the three countries with the highest Case changes are Qatar, Afghanistan, and Somalia; the three countries with the lowest Case changes are the Northern Mariana Islands, Albania, and Puerto Rico (S1 Fig). And the three countries with the highest EAPC are Russian Federation, Italy, and Belarus; the three countries with the lowest EAPC are Oman, Nepal, and Kuwait (Fig 1D).

3.2 Distribution and trends in the DALYs rate of EP

At the global level, there were 0.34 million (95% UI: 0.30–0.38) DALYs in 1990 and 0.38 million (95% UI: 0.32–0.44) DALYs in 2019. In the past 30 years, the AS-DALYs rate decreased with an EAPC of -0.84% (95%CI: from -0.98 to -0.7), dropping from 12.46/100,000 persons (95% UI, 11.09 to 13.91) in 1990 to 9.69/100,000 persons (95% UI, 8.27 to 11.31) in 2019. Over the past three decades, DALYs in middle SDI to high SDI regions have become lower and maintained the highest EAPC of -4.53 (-4.75 to -4.3) with a clear downward trend, while DALYs in low and low-middle SDI regions have not only not decreased but even slightly increased, not only that, the downward trend of EAPC values is not obvious. Looking at the global regions, DALYs generally decreased, but the four regions in Sub-Saharan Africa had the highest AS-DALYs at 60.76/100,000 (44.5 to 77.37). While the Caribbean had the most pronounced increase at 4.45% (3.07 to 6.12), EAPC also had the most pronounced upward trend at 6.11% (5.22 to 7.02) (Table 2). On observation from the GBD regions and countries level, the three countries with the highest AS-DALYs are Chad, Mauritania, and Senegal; the three countries with the lowest AS-DALYs are Poland, Singapore, Cyprus (Fig 1B and S2 Table). The age distribution pattern of DALYs rate in most regions was largely consistent with that of death rate (S2 and S3 Figs).

Table 2. DALYs of ectopic pregnancy in 1990 and 2019 for all locations, with EAPC from 1990 and 2019.

Location 1990 2019 1990–2019
DALYs
No. × 103(95% UI)
AS-DALY
per 100,000
No. (95% UI)
DALYs
No. × 103(95% UI)
AS-DALY
per 100,000
No. (95% UI)
DALYs change
No. (95% UI)
EAPC
No. (95% CI)
Global 339.44 (301.77 to 378.65) 12.46 (11.09 to 13.91) 378.03 (322.55 to 440.09) 9.69 (8.27 to 11.31) 0.11% (-0.07 to 0.31) -0.84% (-0.98 to -0.7)
Socio-demographic index
Low 115.84 (98.28 to 134.88) 51.46 (43.7 to 59.7) 200.33 (164.29 to 239.91) 37.69 (30.83 to 45.33) 0.73% (0.39 to 1.1) -0.97% (-1.11 to -0.82)
Low-middle 116.16 (99.96 to 134.1) 21.57 (18.63 to 24.91) 124.92 (104.84 to 146.25) 13.21 (11.09 to 15.47) 0.08% (-0.11 to 0.3) -1.6% (-1.83 to -1.37)
Middle 73.43 (65.37 to 81.58) 8.04 (7.16 to 8.95) 41.13 (35.01 to 48.43) 3.31 (2.82 to 3.91) -0.44% (-0.54 to -0.33) -3.18% (-3.51 to -2.84)
Middle-high 28.78 (25.58 to 32.24) 4.63 (4.12 to 5.19) 9.1 (7.81 to 10.63) 1.32 (1.14 to 1.55) -0.68% (-0.73 to -0.62) -4.53% (-4.75 to -4.3)
High 5.12 (4.55 to 5.75) 1.19 (1.06 to 1.34) 2.33 (1.99 to 2.73) 0.52 (0.44 to 0.6) -0.54% (-0.61 to -0.48) -2.62% (-2.78 to -2.46)
Region
High-income Asia Pacific 0.63 (0.55 to 0.73) 0.71 (0.62 to 0.82) 0.14 (0.11 to 0.17) 0.19 (0.16 to 0.23) -0.78% (-0.82 to -0.73) -4.75% (-4.97 to -4.53)
Central Asia 0.48 (0.41 to 0.56) 1.3 (1.12 to 1.52) 0.37 (0.3 to 0.45) 0.73 (0.59 to 0.89) -0.23% (-0.34 to -0.11) -1.9% (-2.08 to -1.72)
East Asia 27.22 (22.16 to 33.14) 3.83 (3.12 to 4.68) 5.08 (3.99 to 6.27) 0.7 (0.55 to 0.87) -0.81% (-0.86 to -0.75) -5.73% (-6.17 to -5.29)
South Asia 121.3 (98.97 to 146.95) 23.21 (19.09 to 28.03) 106.31 (83.76 to 131.84) 10.87 (8.56 to 13.47) -0.12% (-0.34 to 0.15) -2.86% (-3.16 to -2.56)
Southeast Asia 19.15 (16.29 to 22.64) 7.87 (6.68 to 9.31) 13.88 (11.44 to 16.41) 3.86 (3.19 to 4.56) -0.28% (-0.43 to -0.08) -2.69% (-2.94 to -2.43)
Australasia 0.08 (0.07 to 0.1) 0.75 (0.61 to 0.91) 0.04 (0.03 to 0.05) 0.28 (0.22 to 0.35) -0.54% (-0.65 to -0.39) -3.35% (-4.03 to -2.66)
Caribbean 0.55 (0.45 to 0.67) 2.83 (2.35 to 3.46) 2.97 (2.22 to 3.88) 12.24 (9.12 to 15.95) 4.45% (3.07 to 6.12) 6.11% (5.22 to 7.02)
Central Europe 0.78 (0.71 to 0.86) 1.29 (1.17 to 1.43) 0.12 (0.1 to 0.16) 0.25 (0.2 to 0.32) -0.84% (-0.87 to -0.8) -5.86% (-6.44 to -5.28)
Eastern Europe 6.82 (5.82 to 7.91) 5.89 (5.02 to 6.86) 0.81 (0.61 to 1.05) 0.81 (0.61 to 1.05) -0.88% (-0.91 to -0.84) -7.64% (-8 to -7.29)
Western Europe 1.39 (1.22 to 1.59) 0.71 (0.63 to 0.82) 0.57 (0.42 to 0.77) 0.31 (0.23 to 0.41) -0.59% (-0.67 to -0.5) -3.05% (-3.21 to -2.89)
Andean Latin America 0.54 (0.45 to 0.66) 2.74 (2.29 to 3.32) 1.73 (1.29 to 2.27) 5.16 (3.85 to 6.76) 2.22% (1.34 to 3.45) 2.07% (1.06 to 3.09)
Central Latin America 4.33 (3.89 to 4.83) 4.91 (4.42 to 5.47) 3.27 (2.69 to 4.03) 2.41 (1.98 to 2.96) -0.25% (-0.39 to -0.06) -2.51% (-2.83 to -2.2)
Southern Latin America 0.38 (0.31 to 0.46) 1.52 (1.26 to 1.84) 0.5 (0.41 to 0.6) 1.47 (1.22 to 1.77) 0.31% (0.07 to 0.62) -0.05% (-0.39 to 0.3)
Tropical Latin America 5.61 (4.76 to 6.59) 6.89 (5.88 to 8.05) 2.79 (2.36 to 3.3) 2.32 (1.97 to 2.75) -0.5% (-0.61 to -0.37) -2.62% (-3.34 to -1.9)
North Africa and Middle East 5.75 (5.06 to 6.49) 3.6 (3.16 to 4.07) 4.51 (3.66 to 5.51) 1.39 (1.13 to 1.7) -0.22% (-0.36 to -0.04) -3.33% (-3.42 to -3.25)
High-income North America 2.67 (2.24 to 3.14) 1.78 (1.49 to 2.09) 1.28 (1.05 to 1.54) 0.78 (0.64 to 0.94) -0.52% (-0.62 to -0.4) -2.4% (-2.71 to -2.1)
Oceania 0.42 (0.33 to 0.52) 13.56 (10.76 to 16.61) 0.8 (0.61 to 1.04) 11.75 (8.98 to 15.26) 0.89% (0.45 to 1.5) -0.59% (-0.86 to -0.32)
Central Sub-Saharan Africa 16.6 (12.59 to 21.08) 69.68 (52.38 to 88.9) 36.76 (26.7 to 46.19) 60.76 (44.5 to 77.37) 1.21% (0.56 to 2.12) 0.29% (-0.03 to 0.61)
Eastern Sub-Saharan Africa 46.52 (38.46 to 54.78) 61.49 (51 to 72.62) 72.11 (58.13 to 87.87) 38.69 (31.14 to 46.9) 0.55% (0.19 to 0.92) -1.47% (-1.59 to -1.35)
Southern Sub-Saharan Africa 15.26 (12.93 to 17.87) 56.75 (47.99 to 66.42) 9.78 (7.26 to 12.69) 22.16 (16.56 to 28.63) -0.36% (-0.54 to -0.14) -1.83% (-2.95 to -0.7)
Western Sub-Saharan Africa 62.98 (50.41 to 79.57) 75.16 (60.23 to 94.67) 114.2 (88.17 to 148.99) 51.49 (39.68 to 66.93) 0.81% (0.36 to 1.39) -1.28% (-1.54 to -1.01)

3.3 Distribution and trends in the death rate of EP

As we mentioned earlier, EP does not cause serious consequences if detected in time, but rupture of EP is a gynecological emergency that can lead to death in women [18]. Globally, there were 5749 (95% UI: 5107 to 6435) deaths from EP in 1990 and 6452 (95% UI: 5496 to 7513) deaths from EP in 2019. Over the last 30 years, ASDR has decreased and continues to show a downward trend from 0.22/100,000 (95% UI, 0.19 to 0.24) in 1990 decreasing to 0.16/100,000 (95% UI, 0.14 to 0.19) in 2019, with an EAPC of -0.91% (95% CI: -1.04 to -0.78).

In terms of SDI, lower SDI does seem to lead to higher ASDR, and this difference can even be tens of times higher. 2019 ASDR in low SDI areas was 0.68 (0.56 to 0.82), while ASDR in high SDI areas was only 0.01 (0.01 to 0.01), and EAPC was higher at -2.95% (-3.13 to– 2.77), suggesting a more pronounced downward trend in high SDI regions along with a decrease in mortality (Table 3).

Table 3. Deaths of ectopic pregnancy in 1990 and 2019 for all locations, with EAPC from 1990 and 2019.

Location 1990 2019 1990–2019
Death cases
No. (95% UI)
ASDR
per 100,000
No. (95% UI)
Death cases
No. (95% UI)
ASDR
per 100,000
No. (95% UI)
Case change
No. (95% UI)
EAPC
No. (95% CI)
Global 5749 (5107 to 6435) 0.22 (0.19 to 0.24) 6452 (5496 to 7513) 0.16 (0.14 to 0.19) 0.12% (-0.06 to 0.32) -0.91% (-1.04 to -0.78)
Socio-demographic index
Low 2032 (1723 to 2359) 0.94 (0.79 to 1.09) 3478 (2849 to 4187) 0.68 (0.56 to 0.82) 0.71% (0.38 to 1.09) -1.02% (-1.15 to -0.89)
Low-middle 1968 (1698 to 2279) 0.38 (0.33 to 0.44) 2126 (1778 to 2495) 0.23 (0.19 to 0.27) 0.08% (-0.11 to 0.3) -1.69% (-1.88 to -1.49)
Middle 1209 (1075 to 1345) 0.14 (0.12 to 0.15) 679 (575 to 802) 0.05 (0.05 to 0.06) -0.44% (-0.54 to -0.32) -3.3% (-3.63 to -2.96)
Middle-high 460 (412 to 514) 0.07 (0.07 to 0.08) 134 (115 to 155) 0.02 (0.02 to 0.02) -0.71% (-0.76 to -0.65) -4.93% (-5.19 to -4.67)
High 78 (70 to 87) 0.02 (0.02 to 0.02) 32 (28 to 36) 0.01 (0.01 to 0.01) -0.59% (-0.65 to -0.52) -2.95% (-3.13 to -2.77)
Region
High-income Asia Pacific 10 (9 to 12) 0.01 (0.01 to 0.01) 2 (1 to 2) 0 (0 to 0) -0.83% (-0.86 to -0.79) -5.67% (-5.88 to -5.45)
Central Asia 6 (6 to 7) 0.02 (0.02 to 0.02) 4 (4 to 5) 0.01 (0.01 to 0.01) -0.29% (-0.41 to -0.14) -2.37% (-2.52 to -2.23)
East Asia 414 (332 to 512) 0.06 (0.05 to 0.07) 65 (49 to 82) 0.01 (0.01 to 0.01) -0.84% (-0.89 to -0.78) -6.45% (-6.96 to -5.93)
South Asia 2040 (1673 to 2471) 0.4 (0.33 to 0.49) 1778 (1397 to 2212) 0.18 (0.14 to 0.23) -0.13% (-0.35 to 0.15) -2.95% (-3.22 to -2.69)
Southeast Asia 323 (273 to 386) 0.14 (0.12 to 0.16) 234 (192 to 276) 0.06 (0.05 to 0.08) -0.28% (-0.43 to -0.07) -2.81% (-3.08 to -2.54)
Australasia 1 (1 to 2) 0.01 (0.01 to 0.01) 1 (0 to 1) 0 (0 to 0) -0.59% (-0.7 to -0.44) -3.89% (-4.69 to -3.08)
Caribbean 9 (7 to 11) 0.05 (0.04 to 0.06) 51 (37 to 67) 0.21 (0.15 to 0.27) 4.9% (3.35 to 6.77) 6.33% (5.41 to 7.27)
Central Europe 12 (11 to 14) 0.02 (0.02 to 0.02) 1 (1 to 1) 0 (0 to 0) -0.9% (-0.92 to -0.88) -7.79% (-8.32 to -7.26)
Eastern Europe 112 (96 to 130) 0.1 (0.08 to 0.11) 8 (6 to 11) 0.01 (0.01 to 0.01) -0.92% (-0.95 to -0.9) -9.34% (-9.78 to -8.9)
Western Europe 19 (18 to 21) 0.01 (0.01 to 0.01) 4 (4 to 5) 0 (0 to 0) -0.77% (-0.8 to -0.74) -5.24% (-5.55 to -4.92)
Andean Latin America 8 (6 to 9) 0.04 (0.03 to 0.05) 28 (20 to 37) 0.08 (0.06 to 0.11) 2.6% (1.55 to 4.06) 2.32% (1.23 to 3.43)
Central Latin America 69 (62 to 76) 0.08 (0.07 to 0.09) 51 (42 to 64) 0.04 (0.03 to 0.05) -0.25% (-0.41 to -0.06) -2.62% (-2.94 to -2.29)
Southern Latin America 5 (4 to 6) 0.02 (0.02 to 0.02) 7 (5 to 8) 0.02 (0.02 to 0.02) 0.37% (0.09 to 0.72) -0.04% (-0.48 to 0.41)
Tropical Latin America 95 (80 to 111) 0.12 (0.1 to 0.14) 46 (39 to 54) 0.04 (0.03 to 0.04) -0.52% (-0.62 to -0.38) -2.78% (-3.54 to -2.02)
North Africa and Middle East 92 (80 to 103) 0.06 (0.05 to 0.07) 71 (57 to 89) 0.02 (0.02 to 0.03) -0.22% (-0.37 to -0.04) -3.43% (-3.52 to -3.34)
High-income North America 42 (35 to 50) 0.03 (0.02 to 0.03) 20 (16 to 24) 0.01 (0.01 to 0.01) -0.53% (-0.63 to -0.4) -2.33% (-2.65 to -2.01)
Oceania 7 (6 to 9) 0.23 (0.18 to 0.29) 13 (10 to 18) 0.2 (0.15 to 0.26) 0.92% (0.46 to 1.54) -0.61% (-0.88 to -0.33)
Central Sub-Saharan Africa 289 (217 to 369) 1.26 (0.94 to 1.61) 643 (468 to 816) 1.1 (0.8 to 1.42) 1.23% (0.56 to 2.16) 0.29% (-0.02 to 0.61)
Eastern Sub-Saharan Africa 848 (704 to 1000) 1.18 (0.98 to 1.39) 1297 (1044 to 1579) 0.73 (0.59 to 0.88) 0.53% (0.17 to 0.89) -1.54% (-1.65 to -1.43)
Southern Sub-Saharan Africa 262 (222 to 308) 1 (0.85 to 1.17) 168 (125 to 217) 0.38 (0.29 to 0.49) -0.36% (-0.54 to -0.15) -1.95% (-3.05 to -0.83)
Western Sub-Saharan Africa 1086 (869 to 1373) 1.35 (1.08 to 1.69) 1959 (1511 to 2554) 0.92 (0.7 to 1.2) 0.8% (0.35 to 1.37) -1.33% (-1.59 to -1.08)

Looking at the GBD region and country level, the three countries with the highest ASDR were Mauritania, Chad, and Senegal; earlier detection of EP did not result in death, so the lowest countries were not listed (Fig 1C and S3 Table). Unlike acute diseases such as acute myocardial infarction, EP has a relatively low lethality rate. Globally, mortality from EP has declined after three decades compared with 1990, but the pattern of its age distribution is essentially the same as before (S2 Fig). By combining morbidity and mortality data, we performed a cluster analysis at the national and regional levels to find countries with similar annual increases. Based on the results of the cluster analysis, 59 countries (or regions) were classified in the "Significant increase" group, including the Netherlands, China, the United Kingdom, and Germany. 90 countries (or regions) were classified in the "Minor increase" group, including Thailand, Mexico, Egypt, and the Republic of Korea. 24 countries (or regions) were classified in the "Stable or minor decrease" group, including Canada, Cuba, Niger, and Chad. The remaining 39 countries (or regions) are classified in the "Significant decrease" group, including Oman, Sudan, Libya, and Yemen (Fig 3).

Fig 3. Cluster analysis of incidence rate and death rate in different countries.

Fig 3

3.4 Correlation analysis of EP related ASIR, ASDR, AS-DALYs and different SDI

In 2019, a significant association was detected between EAPC and ASIR, (ρ = 0.34, p < 0.001), and similarly, a significant association was observed between EAPC and ASDR, (ρ = 0.29, p < 0.001) (Fig 4A). We can observe the ASIR and its expected levels for different SDI regions and countries. High-income North America, High-income Asia Pacific, and Australasia closely followed expected trends over the study period. However, in many other regions, the actual situation is far from the forecast curve, for example, the level in regions such as Oceania and Southern Latin America is much higher than the expected level, however, the level in regions such as Tropical Latin America and Southern Sub-Saharan Africa is much lower than the expected level. The ASIR in most regions gradually declines smoothly along with the rise in SDI, but there are some regions where the ASIR fluctuates sharply, such as Central Asia and Eastern Europe (Fig 4B).

Fig 4.

Fig 4

Correlation analysis. (A) The correlation between EAPC and ASIR/ASDR in 2019. (B) ASIR for EP for different regions and (C) countries and territories by SDI, 1990–2019.

At the overall level, ASDR is significantly negatively correlated with SDI values (R = -0.699, p < 0.001). Most of the high SDI regions have limited their ASDR to a very low level, close to zero, but almost all sub-Saharan Africa regions have higher than expected ASDR values. The case of AS-DALYs is basically a replica of the above (S4A and S4C Fig).

In 2019, there was an inverse relationship between the ASIR of EP and SDI at the national level, with some exceptions (Fig 4C). A similar pattern was observed in the relationship between ASDR and AS-DALYs in relationship to SDI. We can find that some countries are much higher than expected levels, such as Russian Federation, Austria, and Papua New Guinea, while countries at lower SDI, such as Somalia, Chad, and Niger, generally have higher incidence rate, death rate and AS-DALYs, which is consistent with our findings mentioned above (S4B and S4D Fig).

3.5 EP-related risk factors

According to the GBD 2019, we only found one risk factor associated with EP, iron deficiency. Iron deficiency is classified as " Child and maternal malnutrition " and " Behavioral risks ". Globally, 21.9% of deaths and DALYs in patients with EP can be attributed to iron deficiency. Among the five SDI tiers, only the low SDI regions exceeded the global average for the proportion attributed to iron deficiency, reaching 22.8% and 22.9% for the proportion attributed to deaths and DALYs. We can also observe a gradual decrease in the contribution of iron deficiency to deaths and DALYs from low SDI regions to high SDI regions until the proportions reach a minimum of 11.1% and 10.8%, respectively. Regionally, the highest proportion of deaths and DALYs due to iron deficiency was found in sub-Saharan Africa and the lowest in Western Europe, which is consistent with our results above. It is worth noting that all Sub-Saharan Africa regions had more than 20% of EP deaths and DALYs attributable to iron deficiency. Only South Asia and Western Saharan Africa exceeded the global average for both indicators (Fig 5).

Fig 5. Proportion of EP deaths and DALYs attributable to iron deficiency for different SDI regions, 2019.

Fig 5

4. Discussion

EP is a leading cause of maternal morbidity and unexpected death worldwide. The incidence of EP is increasing in developed countries like the United States, while the mortality rate of EP in developing countries continues to rise, leading to a significant disease burden. Previous epidemiological studies have primarily focused on specific countries or regions, lacking a comprehensive global analysis to guide the prevention and treatment of EP [19]. Therefore, this study utilizes GBD 2019 data to provide a comprehensive overview of global epidemiological trends and patterns of EP over the past three decades. This analysis can contribute to the formulation of health policies and the effective allocation of healthcare resources.

EP is highly preventable and treatable, and with early detection, the chances of successful treatment are high, leading to a low risk of mortality. From a global perspective, there has been a decrease in the ASIR, ASDR, and AS-DALYs of EP in 2019 compared to 1990. This decreasing trend indicates improvements in the prevention and treatment of EP, which can be attributed to advancements in various aspects, including social living conditions. The age structure of EP incidence remains stable, with the highest incidence observed in the 25–29 years age group. Furthermore, the trends of mortality and DALYs rates with age are remarkably similar. This similarity may be due to the fact that DALYs in EP are primarily associated with fatal cases. However, it is surprising to note that both mortality and DALYs peak at an earlier age compared to 1990, suggesting a younger age profile of EP deaths. A survey conducted in Washington State, USA, between 1987 and 2014 revealed a decrease in EP hospitalization rates. However, there was an increase in EP-related mortality/severe morbidity among females aged 25–34 years, which aligns with the findings of our study. This outcome may be influenced by increasing low-risk EP patients receiving outpatient methotrexate therapy [20].

SDI represents a country or region’s combined educational, economic, and medical levels. In our analysis of EP incidence rates, we observed a significant decline in EP incidence rates in regions with low SDI, low-middle SDI, and middle SDI. The rate of decline in these regions was higher than the global average. However, in regions with higher SDI, the rate of decline was relatively low. We hypothesize that this discrepancy may be because the ASIR in high SDI regions was already lower than the ASIR in low SDI regions in 2019, as early as 1990. Consequently, the potential for further decline was originally smaller, resulting in a less pronounced decreasing trend. Further research and investigation are necessary to better understand the underlying factors contributing to these trends.

Not only did the ASDR and AS-DALYs show varying degrees of decline in different SDI regions, but the correlation analysis also revealed a negative correlation between all three ASR indicators and SDI. Notably, Sub-Saharan African regions had higher than expected values of ASDR and AS-DALYs, indicating a concerning health situation for women in these low SDI regions. Iceland is a highly developed country, belonging to the High SDI countries, and a study showed that there were no maternal deaths from EP in Iceland from 1985–2009, which is inseparable from good living conditions, universal education levels, and a comprehensive national health care system. These factors play crucial roles in preventing and managing EP incidences [21]. In contrast, low-income groups may face challenges such as lower levels of medical literacy and poorer living and medical conditions. Consequently, these factors could contribute to higher morbidity and mortality rates from EP in low SDI areas compared to high SDI areas [22].

Interestingly, when we analyze the data by age groups, we observe a delayed peak age of incidence in both High SDI areas and High-Middle SDI areas in 2019. In fact, in some age groups, the incidence rates have even exceeded the rates observed thirty years earlier. This delayed peak age of incidence and the increased incidence may be due to a variety of reasons. Firstly, women in higher SDI areas may have higher levels of education and contraceptive use. This may result in fewer early pregnancies and cases of younger EP, thus delaying the peak incidence of EP [23, 24]. Furthermore, it has been suggested that there is a negative correlation between the human development index and fertility rates. Therefore, we can hypothesize that the increased years of education in women may have led to a delay in the age of childbearing, consequently causing a delay in the onset of EP and an increased incidence at certain ages [25].

The EP situation in underdeveloped countries is concerning. The incidence of EP in underdeveloped countries such as Niger and Chad is still among the highest in the world due to a series of implication effects caused by economic backwardness. In addition, the low level of treatment leads to a high mortality rate of EP, whose DALYs can be hundreds or even thousands of times higher than those in developed countries. Previous research has highlighted significant disparities in the management of EP based on factors such as race, region, and access to reliable health insurance. For instance, some women may delay seeking medical care due to a lack of dependable health insurance, consequently increasing their risk of complications and death related to EP [26]. Furthermore, it has been observed that minority populations exhibit higher rates of reproductive tract infections, which can contribute to more severe cases of EP [22]. Addressing these disparities and closing the gap in EP management is challenging. It is influenced by long-standing economic and medical inequalities and limitations associated with factors like educational access and religious beliefs.

Previous studies have identified several common risk factors associated with EP, including reproductive mycoplasma infections, Chlamydia trachomatis infections, pelvic inflammatory disease, and the use of assisted reproductive technology and IUDs [2729]. However, according to the GBD 2019, iron deficiency has emerged as a significant risk factor for EP. The study revealed that more than 20% of EP deaths and DALYs in sub-Saharan Africa were attributed to iron deficiency. Even in regions classified as having a High SDI, the proportion of EP-related deaths and DALYs associated with iron deficiency exceeded 10%. This finding offers a new direction for EP-related research. Furthermore, research has indicated that serum zinc levels are significantly higher in EP patients, while serum copper levels are lower. The copper/zinc ratio has shown potential as a novel diagnostic tool for EP. However, further basic research is needed to verify whether iron deficiency or other micronutrient deficiencies contribute to the development of EP.

The present study has several notable strengths. Firstly, it provides a comprehensive analysis of EP morbidity, mortality, and DALYs over a period of 30 years (1990–2019), offering a valuable overview of the global burden of EP. Additionally, the study examines the influencing factors associated with EP by comparing its conditions in different SDI and age groups, thereby providing new insights and directions for further research on EP. This study is the first-ever global epidemiological study on EP, making it an important reference for EP management. However, despite these strengths, there are some limitations that should be acknowledged. Firstly, the study relies on data from the GBD estimation, which may introduce uncertainty due to variations in data availability across countries and regions. Moreover, the lack of a comprehensive EP surveillance system in certain low and Middle SDI countries/regions further contributes to potential data limitations. Secondly, the study does not differentiate between subtypes or pathological types of EP in the GBD analysis, hindering a more detailed disease analysis. Furthermore, it is worth noting that only one EP-related risk factor, iron deficiency, was included in the study, while common factors such as Chlamydia trachomatis infections and pelvic inflammatory disease were not identified as significant risk factors. This could be considered an incomplete and potentially biased representation of EP risk factors. However, modifying the availability of such data can be challenging.

5. Conclusion

Over the past 30 years, there has been a gradual decrease in the global morbidity, mortality, and DALYs associated with EP. However, it is crucial to note that these indicators are still increasing in economically disadvantaged regions. This trend may be attributed to various factors such as ethnicity, economic status, and educational levels. It is therefore essential to develop effective public health policies that address these disparities and provide enhanced protection for women belonging to ethnic minorities and low-income groups. Additionally, promoting early diagnosis and treatment of EP should be prioritized to mitigate its impact on these vulnerable populations.

Supporting information

S1 Table. Incidence of ectopic pregnancy in 1990 and 2019 for all locations, with EAPC from 1990 and 2019.

(DOCX)

S2 Table. DALYs of ectopic pregnancy in 1990 and 2019 for all locations, with EAPC from 1990 and 2019.

(DOCX)

S3 Table. Deaths of ectopic pregnancy in 1990 and 2019 for all locations, with EAPC from 1990 and 2019.

(DOCX)

S1 Fig. Distribution of case changes in various countries and regions in 2019.

(TIF)

S2 Fig. Distribution of DALYs rate in different SDI regions, age distribution of incidence rate in different SDI regions from 1990–2019.

(TIF)

S3 Fig. Distribution of death rate in different SDI regions, age distribution of incidence rate in different SDI regions from 1990–2019.

(TIF)

S4 Fig. Correlation analysis.

(A) ASDR for EP for different regions and (B) countries and territories by SDI, 1990–2019; (C)AS-DALYs for EP for different regions and (D) countries and territories by SDI, 1990–2019.

(TIF)

Acknowledgments

The authors thank all staff for their contributions to the GBD database.

Data Availability

All relevant data are within the manuscript and its Supporting Information files.

Funding Statement

This project was funded by The National Key Research and Development Program of China (2021YFC2701300), Hubei Key Research and Development Program (2022BCA045) and The National Natural Science Foundation of China (81971364 & 82001527). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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Decision Letter 0

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20 Apr 2023

PONE-D-22-31092Global burden and trends of ectopic pregnancy: An observational trend study from 1990 to 2019PLOS ONE

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We look forward to receiving your revised manuscript.

Kind regards,

Gang Qin, PhD, MD

Academic Editor

PLOS ONE

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5. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Additional Editor Comments:

I agree with the reviewer's comment.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: I appreciate the authors for this intensive research work on the topic “Global burden and trends of ectopic pregnancy: An observational trend study from 1990 to 2019”. The presentation of the data seems strong, and the paper is generally well-written, with an appropriate focus. However, this study may be accepted for publication with the following suggestions and comments for further improvements.

Abstract

Comment 1: The abstract is written with an appropriate focus.

Introduction

Comment 2: The introduction section is poorly written.

Comment 3: In addition to the current contents of the introduction section, add at least two paragraphs in the social context like.

1. What is the situation of EP in developed, developing, and underdeveloped countries? elaborate.

2. How is it changing over time?

3. Where it is still high from the previous literature.

4. Elaborate if it is declining, then why is your study important?

Material and Methods

Comment 4: Written Properly.

Results and Discussion

Comment 5: Figure resolution is very poor. Please provide high-resolution figures.

Comment 6: Add some discussion for underdeveloped and developing countries’ situations.

Comment 7: The conclusion is written very well.

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: Yes: Mayank Singh

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Attachment

Submitted filename: Comments and Suggestions.docx

PLoS One. 2023 Oct 26;18(10):e0291316. doi: 10.1371/journal.pone.0291316.r002

Author response to Decision Letter 0


22 Apr 2023

Dear Editor and reviewer,

Thank you for your letter and for the reviewers' comments concerning our manuscript entitled " Global burden and trends of ectopic pregnancy: An observational trend study from 1990 to 2019" (PONE-D-22-31092). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. Images cannot be uploaded in this section of the submission system, so we have also uploaded a word version including the illustrations, which you can see at the end of the PDF.

First, here is our response to the Journal Requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming.

Response:

First of all, we would like to thank the journal again for their guidance, and we have reworked the manuscript style as requested by the journal.

2. Thank you for stating the following financial disclosure: "The National Key Research and Development Program of China (2018YFC2002204), Hubei Key Research and Development Program (2022BCA045) and The National Natural Science Foundation of China (81971364 & 82001527)."

Please state what role the funders took in the study. If the funders had no role, please state: "The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript."

If this statement is not correct you must amend it as needed.

Please include this amended Role of Funder statement in your cover letter; we will change the online submission form on your behalf.

Response:

The above funds are our funders, but "The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. " And we will explain this again in the cover letter.

3. PLOS requires an ORCID iD for the corresponding author in Editorial Manager on papers submitted after December 6th, 2016. Please ensure that you have an ORCID iD and that it is validated in Editorial Manager. To do this, go to ‘Update my Information’ (in the upper left-hand corner of the main menu), and click on the Fetch/Validate link next to the ORCID field. This will take you to the ORCID site and allow you to create a new iD or authenticate a pre-existing iD in Editorial Manager. Please see the following video for instructions on linking an ORCID iD to your Editorial Manager account: https://www.youtube.com/watch?v=_xcclfuvtxQ

Response:

We double-checked our account and found that the corresponding author's ORCID iD exists in the system, as shown below.

4. Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information.

Response:

We have added the title of the supporting information at the end of the manuscript and updated the references in the manuscript accordingly.

5. We note that Figure 1 in your submission contain [map/satellite] images which may be copyrighted. All PLOS content is published under the Creative Commons Attribution License (CC BY 4.0), which means that the manuscript, images, and Supporting Information files will be freely available online, and any third party is permitted to access, download, copy, distribute, and use these materials in any way, even commercially, with proper attribution. For these reasons, we cannot publish previously copyrighted maps or satellite images created using proprietary data, such as Google software (Google Maps, Street View, and Earth). For more information, see our copyright guidelines: http://journals.plos.org/plosone/s/licenses-and-copyright.

Response:

Thank you for your reminder that we take copyright issues very seriously, so we immediately went to investigate the source of the map. Since our map was generated by R, we investigated the source of the map in the R package (as shown below) and found that it came from Natural Earth (http://www.naturalearthdata.com/), which is in the public domain and therefore does not require special attribution, but we will make the source of the Figure clear in the manuscript.

6. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Response:

We have checked the reference list, and we can now be sure that it is correct.

Here is a point-by-point response to the comments and concerns of the reviewers.

Comment 1: The abstract is written with an appropriate focus.

Comment 4: Written Properly.

Comment 7: The conclusion is written very well.

Response:

Thank you very much for your recognition of our work, and I believe that with your suggestions, our article will be more rigorous and more valuable.

Comment 2: The introduction section is poorly written.

Response:

We are very sorry for the poorly written introduction, we have revised the manuscript according to your comments and added the key missing parts you suggested, thank you very much for your pointers.

Comment 3: In addition to the current contents of the introduction section, add at least two paragraphs in the social context like.

1. What is the situation of EP in developed, developing, and underdeveloped countries? elaborate.

2. How is it changing over time?

3. Where it is still high from the previous literature.

4. Elaborate if it is declining, then why is your study important?

Response:

Your suggestions were meticulous and thoughtful, and we have added to the content of the manuscript.

Comment 5: Figure resolution is very poor. Please provide high-resolution figures.

Response:

We are very sorry that it affects the readability of the article. The images we uploaded in the system are very clear, but the image quality is compressed when the system automatically generates PDF files, so you can download the original images we uploaded by clicking the download button on the top right corner of the image (as shown in the picture), thank you very much for your patience.

Comment 6: Add some discussion for underdeveloped and developing countries’ situations.

Response:

As you suggested we have added a discussion of underdeveloped and developing countries to the manuscript.

We are very grateful to the editor and reviewers for giving us this opportunity to revise the manuscript. We have tried our best to improve the manuscript, made some changes to the manuscript, and responded to the reviewers' questions one by one. We have uploaded the Manuscript and Revised Manuscript with Track Changes. We appreciate for editor and reviewers' warm work earnestly, and hope that the correction will meet with approval. Once again, thank you very much for your comments and suggestions.

Thank you and best regards.

Yours sincerely,

Shufei Zhang

Corresponding author:

Li Hong, Ph.D.

E-mail: dr_hongli@whu.edu.cn

Attachment

Submitted filename: Response to Reviewers.docx

Decision Letter 1

Gang Qin

3 Jul 2023

PONE-D-22-31092R1Global burden and trends of ectopic pregnancy: An observational trend study from 1990 to 2019PLOS ONE

Dear Dr. Hong,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

==============================

ACADEMIC EDITOR: Pls revise according to the reviewer's suggestions.

==============================

Please submit your revised manuscript by Aug 17 2023 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

  • A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.

  • A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.

  • An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Gang Qin, PhD, MD

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Partly

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: No

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: No

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: Introduction:

1. The introduction section is poorly written

2. There is no need to discuss diagnosis and treatment in the introduction

Methods

1. Study data was obtained from The Global Burden of Disease Study 2019 was modeled by by the Institute for Health Metrics and Evaluation (IHME). SDI data obtained from Global Health Data Exchange (GHDx)

2. Global Burden of Disease Study 2019 should be introduced in details

3. SDI classes should be explained

4. How is EP defined in GED protocols?

5. Age-standardized incidence rate, mortality rate and DALY rate were defined in GBD, why haven't researchers used them and recalculated?

6. “EAPCs were calculated using a linear regression model as follows: ln (ASR) = α + β x + ε,” is incorrect

7. R language version 4.2.1 is incorrect, R software is correct

Results

1. 3.1 Distribution and trends in the incidence rate of EP by age or year???

2. Figures resolution is very poor. Please provide high-resolution figures

3. Figure 2 is unclear

4. the 0-14 and e 55+ years age groups should be excluded

5. the results of EP-related risk factors not well presented

discussion

1. discussion section is weak

2. advantage and limitation were missed

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: Yes: Fatemeh khosravi Shadmani

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

PLoS One. 2023 Oct 26;18(10):e0291316. doi: 10.1371/journal.pone.0291316.r004

Author response to Decision Letter 1


17 Jul 2023

Dear Editors and Reviewers,

Thank you for your letter and for the reviewers' comments concerning our manuscript entitled " Global burden and trends of ectopic pregnancy: An observational trend study from 1990 to 2019" (PONE-D-22-31092R1). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research.

First, here is our response to the Journal Requirements.

1. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Response:

Thank you for your patience in reviewing the manuscript, we have checked all the references to ensure that none of them have been withdrawn, and although we have changed some references, we can be sure that the reference list is correct.

Here are our responses to the reviewers' general comments

We truly appreciate your suggestions on our manuscript and are very sorry that the article's readability has been reduced due to our writing, so we have tried our best to polish the language in the revised manuscript. As for the statistical issues, we have also made changes and deletions based on your suggestions. We hope the revised manuscript could be acceptable to you.

Here is a point-by-point response to the comments and concerns of the reviewers.

Comments on the introduction:

1. The introduction section is poorly written

Response:

We sincerely apologize for our poor writing, and we have carefully and completely rewritten the Introduction section of the manuscript.

2. There is no need to discuss diagnosis and treatment in the introduction

Response:

Thank you very much for your suggestions, we couldn't agree with you more, so we have removed the relevant content and have carefully rewritten this section, and we hope that these changes will fulfill your requirements for the manuscript.

Comments on the Methods:

1. Study data was obtained from The Global Burden of Disease Study 2019 was modeled by the Institute for Health Metrics and Evaluation (IHME). SDI data obtained from Global Health Data Exchange (GHDx)

Response:

First of all, thank you very much for your suggestions, we have added this important information to the revised manuscript.

Line 62-64, “Study data was obtained from GBD 2019 was modeled by the Institute for Health Metrics and Evaluation (IHME)” was added.

Line 70-71, “SDI data was obtained from Global Health Data Exchange (GHDx)” was added.

2. Global Burden of Disease Study 2019 should be introduced in details

Response:

We are very sorry for our omission of this important section, so we have added an introduction to the Global Burden of Disease Study 2019 in the revised manuscript.

Line 53-55, “Explore results from the 2019 Global Burden of Disease study (GBD 2019), which published epidemiological data related to 369 diseases/injuries and 286 causes of death, covered EP in 204 countries and territories from 1990 to 2019” was added.

References:

http://doi.org/10.1016/j.ajp.2023.103677

3. SDI classes should be explained

Response:

We are very sorry that our description of SDI was not clear, so we have made it explicit in the revised manuscript.

Line 65-69, “The Socio-demographic Index (SDI) is a composite indicator of development status strongly correlated with health outcomes. It is the geometric mean of 0 to 1 indices of total fertility rate under the age of 25, mean education for those ages 15 and older and lag distributed income per capita. As a composite, a location with an SDI of 0 would have a theoretical minimum level of development relevant to health, while a location with an SDI of 1 would have a theoretical maximum level” was added.

References:

https://ghdx.healthdata.org/sites/default/files/record-attached-files/IHME_GBD_2019_SDI_1950_2019_INFO_SHEET_Y2021M08D16.PDF

4. How is EP defined in GBD protocols?

Response:

Thank you very much for your suggestion regarding the definition of ectopic pregnancy, which is a very important issue. We have managed to find the GBD definition of ectopic pregnancy after a careful search of the sources and have added it to the revised manuscript.

Line 61, “In GBD, EP is defined as pregnancy occurring outside of the uterus.” was added.

References:

https://www.healthdata.org/results/gbd_summaries/2019/ectopic-pregnancy-level-4-cause

5. Age-standardized incidence rate, mortality rate and DALY rate were defined in GBD, why haven't researchers used them and recalculated?

Response:

Thank you very much for your suggestion, we have calculated the Age-standardized incidence rate, mortality rate, and DALY rate in the table and abbreviated them as ASIR, ASDR, and AS-DALYs in the Method section and have used them for calculation and visualization in the results.

6. “EAPCs were calculated using a linear regression model as follows: ln (ASR) = α + β x + ε,” is incorrect

Response:

Thank you for your correction, we have corrected it in the revised manuscript.

Line 77-78, “EAPCs were calculated using a linear regression model as follows: ln (ASR) = α + β x + ε” was corrected as “The EAPC is calculated by fitting the linear regression line: Y = α + βx + ε, where y represents ln(ASR) and x refers to the calendar year.”.

7. R language version 4.2.1 is incorrect, R software is correct

Response:

Thanks again for the correction; we have also corrected it in the revised manuscript.

Line 87, “R language” was corrected as “R software”.

Comments on the Results:

1. 3.1 Distribution and trends in the incidence rate of EP by age or year???

Response:

Thank you very much for your patience, we have corrected several titles that did not make sense in the revised manuscript.

Line 91, “3.1 Distribution and trends in the incidence rate of EP by age or year” was corrected as “3.1 Distribution and trends in the incidence rate of EP”.

Line 115, “3.2 Distribution and trends in the DALYs rate of EP by age or year” was corrected as “3.2 Distribution and trends in the DALYs rate of EP”.

Line 133, “3.3 Distribution and trends in the Death rate of EP by age or year” was corrected as “3.3 Distribution and trends in the Death rate of EP”.

2. Figures resolution is very poor. Please provide high-resolution figures

Response:

We are very sorry that the unclear figures have caused problems for your review, we have remade and uploaded all the figures and ensured their clarity. However, the journal requires that figures should not exceed 10M in size, so there may be some figures with crowded and unclear details.

3. Figure 2 is unclear

Response:

Thanks for your suggestion, we have recreated and uploaded a clear figure 2.

4. the 0-14 and e 55+ years age groups should be excluded

Response:

We acknowledge that it may be unreasonable to discuss ectopic pregnancies in women under 14 years old or over 55 years old, therefore, we excluded cases in these two age groups and re-visualized them, as shown in Figure 2, S4 Figure, and S5 Figure.

5. the results of EP-related risk factors not well presented

Response:

Thank you for your suggestion and we recognize the limitations of this study in terms of the risk factors associated with ectopic pregnancy. This is because GBD 2019 contains only one risk factor for ectopic pregnancy, iron deficiency, and therefore we have only explored it in the manuscript. We have also rewritten this section in the revised manuscript, and we hope that these changes will help the reader better understand the contents of the manuscript.

Comments on the discussion:

1. discussion section is weak

Response:

Thank you very much for your patient suggestions, we have carefully rewritten the discussion section of the manuscript. The revised manuscript provides a comprehensive analysis of the condition of ectopic pregnancy on several levels.

2. advantage and limitation were missed

Response:

We recognize that an exploration of the advantages and limitations of this study was missing from our manuscript, so in the revised manuscript, we have added this section. Thanks to your suggestions, this makes our manuscript better.

Line 271-286, “The present study has several notable strengths. Firstly, it provides a comprehensive analysis of EP morbidity, mortality, and DALYs over a period of 30 years (1990-2019), offering a valuable overview of the global burden of EP. Additionally, the study examines the influencing factors associated with EP by comparing its conditions in different SDI and age groups, thereby providing new insights and directions for further research on EP. This study is the first-ever global epidemiological study on EP, making it an important reference for EP management. However, despite these strengths, there are some limitations that should be acknowledged. Firstly, the study relies on data from the GBD estimation, which may introduce uncertainty due to variations in data availability across countries and regions. Moreover, the lack of a comprehensive EP surveillance system in certain low and Middle SDI countries/regions further contributes to potential data limitations. Secondly, the study does not differentiate between subtypes or pathological types of EP in the GBD analysis, hindering a more detailed disease analysis. Furthermore, it is worth noting that only one EP-related risk factor, iron deficiency, was included in the study, while common factors such as Chlamydia trachomatis infections and pelvic inflammatory disease were not identified as significant risk factors. This could be considered an incomplete and potentially biased representation of EP risk factors. However, modifying the availability of such data can be challenging.” was added.

We are very grateful to the editor and reviewers for giving us this opportunity to revise the manuscript. We have tried our best to improve the manuscript, made some changes to the manuscript, and responded to the reviewers' questions one by one. We have uploaded the Manuscript and Revised Manuscript with Track Changes. We appreciate for editor and reviewers' warm work earnestly and hope that the correction will meet with approval. Once again, thank you very much for your comments and suggestions.

Thank you and best regards.

Yours sincerely,

Shufei Zhang

Corresponding author:

Li Hong, Ph.D.

E-mail: dr_hongli@whu.edu.cn

Attachment

Submitted filename: Response to Reviewers.docx

Decision Letter 2

Gang Qin

29 Aug 2023

Global burden and trends of ectopic pregnancy: An observational trend study from 1990 to 2019

PONE-D-22-31092R2

Dear Dr. Hong,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Kind regards,

Gang Qin, PhD, MD

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Acceptance letter

Gang Qin

31 Aug 2023

PONE-D-22-31092R2

Global burden and trends of ectopic pregnancy: An observational trend study from 1990 to 2019

Dear Dr. Hong:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

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Kind regards,

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on behalf of

Dr. Gang Qin

Academic Editor

PLOS ONE

Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Supplementary Materials

    S1 Table. Incidence of ectopic pregnancy in 1990 and 2019 for all locations, with EAPC from 1990 and 2019.

    (DOCX)

    S2 Table. DALYs of ectopic pregnancy in 1990 and 2019 for all locations, with EAPC from 1990 and 2019.

    (DOCX)

    S3 Table. Deaths of ectopic pregnancy in 1990 and 2019 for all locations, with EAPC from 1990 and 2019.

    (DOCX)

    S1 Fig. Distribution of case changes in various countries and regions in 2019.

    (TIF)

    S2 Fig. Distribution of DALYs rate in different SDI regions, age distribution of incidence rate in different SDI regions from 1990–2019.

    (TIF)

    S3 Fig. Distribution of death rate in different SDI regions, age distribution of incidence rate in different SDI regions from 1990–2019.

    (TIF)

    S4 Fig. Correlation analysis.

    (A) ASDR for EP for different regions and (B) countries and territories by SDI, 1990–2019; (C)AS-DALYs for EP for different regions and (D) countries and territories by SDI, 1990–2019.

    (TIF)

    Attachment

    Submitted filename: Comments and Suggestions.docx

    Attachment

    Submitted filename: Response to Reviewers.docx

    Attachment

    Submitted filename: Response to Reviewers.docx

    Data Availability Statement

    All relevant data are within the manuscript and its Supporting Information files.


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