Abstract
Cervical cerclage is an established procedure for treating cervical insufficiency; however, its efficacy in twin pregnancies remains uncertain. This study aimed to evaluate the effectiveness of transvaginal cervical cerclage in twin pregnancies complicated by cervical insufficiency. Data were retrospectively collected from 155 women with twin pregnancies diagnosed with cervical insufficiency. Participants were divided into two groups: the cerclage group (n = 131) and the non-cerclage group (n = 24). The cerclage group was further subdivided into emergency cerclage and ultrasound-indicated cerclage subgroups for detailed analysis. The duration of gestation was found to be longer in the cerclage group compared to the non-cerclage group. Procedures performed included both emergency and ultrasound-indicated cerclage. No significant difference in gestational outcomes was observed between the ultrasound-indicated cerclage subgroup and the non-cerclage group, regardless of cervical length (< 15 mm, < 25 mm, or 15–25 mm). In contrast, a significant improvement in gestational outcomes was noted in the emergency cerclage subgroup compared to the non-cerclage group, irrespective of cervical dilation (> 1 cm or ≤ 1 cm). Overall, cervical cerclage appears to improve pregnancy outcomes in twin pregnancies under specific conditions. While ultrasonographically indicated cerclage did not significantly enhance pregnancy outcomes, emergency cerclage may be effective in improving perinatal prognosis.
Keywords: Cervical insufficiency, Twin pregnancy, Cervical cerclage, Ultrasound
Subject terms: Outcomes research, Reproductive disorders
Introduction
Cervical insufficiency refers to painless, progressive shortening and dilatation of the cervix before 37 weeks gestation, leading to adverse pregnancy outcomes, such as miscarriage or preterm delivery1–3. With the increase in age of pregnant women and the development of assisted reproductive technologies, the incidence of twin pregnancy is increasing4. Women with twin pregnancies are more likely to have cervical insufficiency than those with singleton pregnancies5. The population-based preterm birth rate in the United States is 60.32% in twin pregnancies, which is six times higher than the rate in singleton pregnancies6.
Cervical cerclage is an effective procedure for treating cervical insufficiency, of which McDonald’s cervical cerclage has been widely used and recommended3. While cervical cerclage has demonstrated good outcomes in singleton pregnancies with cervical insufficiency1–3,7–9, the results vary in twin pregnancies. Some studies have concluded that cervical cerclage does not improve the outcomes of twin pregnancies10–13. However, one study showed that when the cervical length was < 15 mm, cervical cerclage prolonged gestation by an average of 2.89 weeks, thereby reducing the risk of preterm birth14. Moreover, cervical cerclage prolongs gestational age by 6.78 weeks in twin pregnancies with cervical dilatation > 1 cm, reduces the risk of preterm birth before 34 weeks, and improves perinatal outcomes14. A recent study also showed that when the cervical length was < 15 mm, the preterm birth rate was lower in the cerclage group by 32, 34, and 37 weeks than in the control group15. Therefore, the use of cervical cerclage in twin pregnancies remains controversial, and further research is necessary.
Therefore, despite existing literature, the use of cervical cerclage in twin pregnancies remains controversial, and further research is necessary. In this retrospective study, we investigated twin pregnancies complicated by cervical insufficiency and evaluated the effect of cervical cerclage on pregnancy outcomes. The primary outcome measures were gestational duration and neonatal outcomes, comparing pregnancies that received cerclage to those that did not. Furthermore, we distinguished between ultrasound-indicated cervical cerclage and emergency cervical cerclage based on the indications for the procedures. Our study contributes to the assessment of the efficacy of cervical cerclage in twin pregnancies and in these conditions above.
Materials and methods
Data were collected from women with twin pregnancies complicated with cervical insufficiency between January 1, 2017, and December 31, 2021, at Xiangya Hospital of Central South University in Changsha, Hunan, China. Xiangya Hospital is a tertiary referral teaching hospital serving the central and southern regions of China, with an average of over 3,500 deliveries in the obstetrics department annually. The twin birth rate was 31.2 per 1,000 births in the United States4. As our hospital is the center for critical pregnancies in our province, we have a relatively high proportion of twin pregnancies as 54 per 1,000 births. Two independent authors examined the medical records of all twin pregnancies complicated with cervical insufficiency, independently determined inclusion and exclusion of study subjects, and cross-checked their results. In cases of disagreement, a third author was consulted to reach a consensus. Data on demographics and obstetric outcomes were collected from the hospital database (electronic hospital information system). The specific variables included: age, height, pre-pregnancy weight, mode of conception, chorionicity, gestational age, mode of delivery, history of cervical surgery and preterm labor, gestational age at diagnosis of cervical insufficiency, cervical length and width on preoperative physical examination and ultrasound, gestational age at delivery, preterm rupture of membranes, chorioamnionitis, birth weight, Apgar scores, neonatal intensive care unit admissions, and neonatal deaths.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institution, and informed consent was obtained. The study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the Medical Ethics Committee of the hospital (202112275).
Participants were eligible for inclusion if they had twin pregnancies in the second trimester with cervical insufficiency, characterized by painless cervical shortening (cervical length < 25 mm on transvaginal ultrasound) or painless cervical dilation, with or without prolapsed membranes, in the absence of significant uterine contractions. Exclusion criteria included the onset of labor, defined as regular uterine contractions with cervical shortening lasting more than 12 h, as well as severe complications such as severe intrauterine infection, preeclampsia, placental abruption, twin-to-twin transfusion syndrome, or serious medical/surgical conditions. Other exclusion criteria were fetal abnormalities, premature rupture of membranes before treatment, early selective fetal reduction, previous cervical cerclage, or incomplete data.
Although international guidelines on ultrasound screening for cervical insufficiency in twin pregnancies have not been standardized, in line with previous studies16,17, at least one cervical ultrasound was typically performed for all twin pregnancies between 14 and 24 weeks of gestation, as recommended for singleton pregnancies1. For pregnant women with a history of cervical conization, cervical cerclage, preterm labor, or late miscarriage, screening was advanced to 12 weeks of gestation. A pelvic examination was conducted during the same appointment, and both vaginal and cervical swabs were collected for microbiologic analyses to rule out infection. The decision to proceed with either cerclage or non-cerclage management was made collaboratively among the woman, her family, and the attending obstetrician. Women were typically discharged 2–7 days after cerclage. Follow-up instructions included avoidance of heavy labor, rest, and an outpatient visit 2 weeks later.
The patients were divided into the cerclage group and non-cerclage group. The cerclage group was further subdivided into the emergency cerclage subgroup and ultrasound-indicated cerclage subgroup for further analysis. Emergency cerclage was indicated for participants presenting with complete cervical dilation on pelvic examination or transvaginal ultrasound during mid-pregnancy, despite no significant contractions, with or without prolapsed membranes. The indication for ultrasound-indicated cerclage was based on transvaginal ultrasound findings of a closed cervical orifice and a cervical length of < 25 mm. While a cervical length of less than 25 mm is widely accepted as the ultrasound cutoff1–3, some studies suggest that ultrasonographically indicated cerclage can significantly prolong gestation and reduce the rate of preterm birth when the cervical length is < 15 mm14,15,18. Additionally, several studies indicate that cervical cerclage prolongs gestation and reduces the risk of preterm birth in twin pregnancies with cervical dilation > 1 cm14,19–21. To refine our study, results were further stratified by cervical dilation (> 1 cm or ≤ 1 cm) for emergency cerclage and by cervical length (< 15 mm, < 25 mm, or 15–25 mm) for ultrasound-indicated cerclage. This stratification facilitated a comparison of pregnancy outcomes with and without cerclage across various cervical conditions.
Statistical analyses were performed using SPSS 22.0 software. Due to the small sample size, measurement data are expressed as median (interquartile range, IQR), and count data are presented as n (%). Categorical variables were compared using the χ² test or Fisher’s exact test, while continuous variables were compared using the Mann–Whitney U test. P value of < 0.05 was considered statistically significant. Kaplan-Meier survival curves and log-rank tests were employed to compare gestational age at delivery between the cervical cerclage and non-cerclage groups, with the x-axis representing gestational weeks at delivery and the y-axis showing the cumulative proportion of women who had not yet delivered.
Results
During the study period, 198 participants met the inclusion criteria. However, 18 cases were excluded due to the presence of severe comorbidities or complications, while 14 cases were excluded following premature rupture of membranes prior to treatment. Additionally, 4 cases were disqualified due to the onset of labor symptoms before treatment, 1 case had a history of cervical cerclage performed before pregnancy, and 4 cases underwent selective fetal reduction as a result of fetal chromosomal abnormalities. Lastly, 3 cases were excluded due to incomplete data and unsuccessful follow-up through phone calls. In total, 155 cases were included in the final analysis: 131 women underwent transvaginal cervical cerclage, while 24 received non-surgical treatment (Fig. 1). All cerclage procedures were successfully performed without perioperative complications.
Fig. 1.
Study flow chart.
Significant differences in the number of pregnancies, gestational age at diagnosis, cervical length, and cervical dilation were observed between the cerclage and non-cerclage groups (Table 1).
Table 1.
Demographic and gestational characteristics.
| Cerclage (n = 131) | Non-cerclage (n = 24) | P | |
|---|---|---|---|
| Maternal age (years) | 31.0 (5.0) | 31.0 (3.5) | 0.909 |
| BMI (kg/m2) | 22.0 (4.4) | 22.0 (2.1) | 0.988 |
| Method of conception | 1.000 | ||
| Natural conception | 10 (7.6%) | 2 (8.3%) | |
| IVF/ICSI | 121 (92.4%) | 22 (91.7%) | |
| Chorionicity | 0.060 | ||
| Monochorionic diamniotic | 12 (9.2%) | 6 (25.0%) | |
| Dichorionic diamniotic | 119 (90.8%) | 18 (75.0%) | |
| Gravidity (times) | 2.0 (3.0) | 1.0 (1.0) | 0.004 |
| Parity (n, %) | 0.092 | ||
| Primigravida | 31 (23.7%) | 2 (8.3%) | |
| Multigravida | 100 (76.3%) | 22 (91.7%) | |
| Prior cervical surgery | 17 (13.0%) | 0 | 0.130 |
| Prior preterm births (14–37 weeks) | 28 (21.4%) | 0 | 0.027 |
| GA at diagnosis (week) | 21.0 (9.0) | 25.0 (5.0) | < 0.001 |
| Ruler measurement of cervical length (mm) | 15.0 (5.0) | 5.0 (13.0) | 0.003 |
| Transvaginal ultrasonographic cervical length (mm) | 21.0 (16.0) | 12.5 (18.0) | 0.001 |
| Cervical dilation at diagnosis (cm) | 0.0 (0.0) | 0.0 (2.5) | < 0.001 |
| Transvaginal ultrasonographic cervical dilation (cm) | 0.2 (1.4) | 0.9 (1.9) | 0.025 |
Data are presented as median (interquartile range, IQR) or numbers (percentages). Categorical variables were compared using the χ2 or Fisher’s exact test. Continuous variables were compared using the Mann–Whitney U test.
BMI body mass index, IVF/ICSI in vitro fertilization/intra cytoplasmic sperm injection, GA gestational age.
Preterm labor before 24 weeks was less frequent in the cerclage group, and the number of prolonged gestational weeks was greater. Labor occurred later in the cerclage group, and the neonatal Apgar score at 1 min was higher (Table 2). The Kaplan-Meier curve also demonstrated significantly longer gestational periods in the cerclage group (Fig. 2).
Table 2.
Overall comparison between the cerclage and non-cerclage groups.
| Cerclage (n = 131) | Non-cerclage (n = 24) | P | OR (95% CI) or MD (95% CI) | |
|---|---|---|---|---|
| GA at delivery (weeks) | 35.0 (5.0) | 32.5 (9.5) | 0.032 | 2.50 (1.81, − 5.54) |
| PTB < 37 | 110 (80.9%) | 22 (91.7%) | 0.322 | 0.39 (0.09, 1.75) |
| PTB < 34 | 55 (40.4%) | 13 (54.2%) | 0.210 | 0.54 (0.23, 1.30) |
| PTB < 28 | 18 (15.6%) | 7 (29.2%) | 0.094 | 0.34 (0.12, 0.94) |
| PTB < 24 | 6 (4.4%) | 5 (20.8%) | 0.013 | 0.15 (0.04, 0.57) |
| GA at diagnosis (weeks) | 21.0 (9.0) | 25.0 (5.0) | < 0.001 | − 4.00 (− 5.23, − 2.40) |
| Latency period from diagnosis to delivery (weeks) | 13.1 (9.5) | 6.85 (6.8) | < 0.001 | 6.25 (4.95, 8.41) |
| Delivery mode | 0.110 | 2.78 (1.05, 7.34) | ||
| Vaginal delivery | 23 (16.9%) | 8 (33.3%) | ||
| Cesarean section | 113 (83.1%) | 16 (66.7%) | ||
| PPROM | 42 (30.9%) | 8 (33.3%) | 0.811 | 0.91 (0.36, 2.30) |
| Clinical chorioamnionitis | 5 (3.7%) | 0 | 1.000 | 2.13 (0.11, 39.79) |
| Perinatal mortality | 32 (12.2%) | 6 (12.5%) | 0.956 | 1.03 (0.40, 2.61) |
| Birth weight (g) | 2150.0 (970.0) | 2037.5 (867.5) | 0.229 | 112.5 (18.41, 309.08) |
| Apgar at 1 min | 10.0 (2.0) | 9.0 (3.0) | 0.030 | 1.00 (0.81, 1.70) |
| Apgar at 5 min | 10.0 (0.0) | 10.0 (1.25) | 0.080 | 0.00 (0, 0.28) |
| Admission to the NICU | 171 (65.3%) | 32 (66.7%) | 0.851 | 0.94 (0.49,1.80) |
Data are presented as median (interquartile range, IQR) or numbers (percentages). Categorical variables were compared using the χ2 or Fisher’s exact test. Continuous variables were compared using the Mann–Whitney U test. Neonatal data were collected from both twins.
GA gestational age, NICU neonatal intensive care unit, PPROM preterm premature rupture of membranes, OR odds ratio, CI confidence interval, MD median difference.
Fig. 2.
Kaplan–Meier curve showing the gestational age between the two groups (overall cerclage and non-cerclage).
Procedures included emergency cervical cerclage and ultrasound-indicated cervical cerclage, followed by subgroup comparisons. Regardless of cervical length (< 15 mm, < 25 mm, or 15–25 mm), there was no significant difference in gestational age at delivery between the ultrasound-indicated cerclage subgroup and the control group. However, irrespective of cervical dilation (> 1 cm or ≤ 1 cm), the gestational age at delivery was significantly higher in the emergency cerclage subgroup compared to the non-cerclage subgroup (Table 3; Figs. 3 and 4).
Table 3.
Pregnancy outcomes of cervical cerclage subgroups.
| Emergency cervical cerclage | ||||
|---|---|---|---|---|
| Cerclage (n = 45) | Non-cerclage (n = 8) | P | OR (95% CI)or MD (95% CI) | |
| GA at delivery (weeks) | 34.0 (6.0) | 23.0 (1.8) | 0.001 | 11.00 (9.60, 11.97) |
| PTB < 37 | 36 (80.0%) | 8 (100.0%) | 0.380 | 0.23 (0.01, 4.28) |
| PTB < 34 | 20 (44.4%) | 7 (87.5%) | 0.063 | 0.11 (0.01, 1.01) |
| PTB < 32 | 14 (33.1%) | 7 (87.5%) | 0.009 | 0.07 (0.01, 0.58) |
| PTB < 28 | 8 (17.8%) | 7 (87.5%) | < 0.001 | 0.03 (0.00, 0.29) |
| PTB < 24 | 2 (4.4%) | 5 (62.5%) | < 0.001 | 0.03 (0.00, 0.29) |
| GA at diagnosis (weeks) | 23.0 (3.0) | 22.5 (2.3) | 0.659 | 0.50 (− 0.20, 1.75) |
| Latency period from diagnosis to delivery (weeks) | 11.0 (6.1) | 0.6 (1.1) | < 0.001 | 10.45 (9.02, 11.03) |
| Delivery mode | 0.001 | 24.50 (2.69, 223.34) | ||
| Vaginal delivery | 10 (22.2%) | 7 (87.5%) | ||
| Cesarean section | 35 (77.8%) | 1 (12.5%) | ||
| PPROM | 12 (26.7%) | 2 (25.0%) | 1.000 | 1.09 (0.19, 6.16) |
| Clinical chorioamnionitis | 1 (2.2%) | 0 | 1.000 | 0.57 (0.02, 15.28) |
| Perinatal mortality | 13 (14.4%) | 12 (75.0%) | < 0.001 | 0.06 (0.02, 0.20) |
| Birth weight (g) | 2000.0 (963.8) | 700.0 (270.0) | 0.002 | 1300.00 (1140.51, 1405.98) |
| Apgar at 1 min | 10.0 (4.0) | 2.5 (7.5) | 0.002 | 7.50 (6.84, 10.44) |
| Apgar at 5 min | 10.0 (1.0) | 4.0 (8.5) | 0.005 | 6.00 (5.83, 9.34) |
| Admission to the NICU | 61 (79.2%) | 4 (25.0%) | 0.157 | 0.26 (0.06,1.17) |
| Ultrasound-indicated cerclage | ||||
|---|---|---|---|---|
| Cerclage (n = 86) | Non-cerclage (n = 16) | P | OR (95% CI) or MD (95% CI) | |
| GA at delivery (weeks) | 35.0 (4.0) | 34.0 (3.3) | 0.659 | 1.00 (0.32, 2.28) |
| PTB < 37 | 70 (81.4%) | 14 (87.5%) | 0.817 | 1.60 (0.33, 7.75) |
| PTB < 34 | 31 (36%) | 6 (37.5%) | 0.912 | 1.07 (0.35, 3.21) |
| PTB < 28 | 8 (9.3%) | 0 | 0.445 | 3.57 (0.20, 65.02) |
| PTB < 24 | 3 (3.5%) | 0 | 1.000 | 1.38 (0.07, 28.06) |
| GA at diagnosis (weeks) | 16.0 (9.0) | 26.5 (3.0) | < 0.001 | − 10.5 (− 12.02, − 9.32) |
| Latency period from diagnosis to delivery(week) | 17.0 (10.2) | 8.3 (2.6) | < 0.001 | 8.70 (6.97, 9.70) |
| Delivery mode | 0.843 | 1.97 (0.24, 16.59) | ||
| Vaginal delivery | 10 (11.6%) | 1 (6.3%) | ||
| Cesarean section | 76 (88.4%) | 15 (93.8%) | ||
| PPROM | 29 (33.7%) | 6 (37.5%) | 0.770 | 1.18 (0.39, 3.57) |
| Clinical chorioamnionitis | 4 (4.7%) | 0 | 1.000 | 1.80 (0.09, 35.06) |
| Perinatal mortality | 12 (7.0%) | 1 (3.1%) | 0.671 | 2.33 (0.29, 18.54) |
| Birth weight (g) | 2150.0 (970.0) | 2135.0 (670.0) | 0.783 | 15.00 (− 97.88, 200.95) |
| Apgar at 1 min | 10.0 (1.0) | 10.0 (2.0) | 0.572 | 0.00 (− 0.12, 0.56) |
| Apgar at 5 min | 10.0 (0.0) | 10.0 (0.3) | 0.889 | 0.00 (0, 0.07) |
| Admission to the NICU | 112 (69.1%) | 27 (84.4%) | 0.080 | 2.41 (0.88, 6.62) |
Data are presented as median (interquartile range, IQR) or as number (percentage). Categorical variables were compared using χ2 or Fisher exact tests. Continuous variables were compared using Mann–Whitney’s U test. Neonatal data were collected from both twins.
GA gestational age, NICU neonatal intensive care unit, PPROM preterm premature rupture of membranes, OR odds ratio, CI confidence interval, MD median difference.
Fig. 3.
Kaplan–Meier curve showing the gestational age between the two subgroups (emergency cerclage and ultrasound-guided cerclage).
Fig. 4.
Kaplan–Meier curve showing the gestational age among the subgroups (cervical length and dilation).
Discussion
We retrospectively evaluated surgical treatment for cervical insufficiency in twin pregnancies, comparing the effects of transvaginal cervical cerclage with expectant treatment on pregnancy outcomes. Cervical cerclage was found to be effective in treating cervical insufficiency in twin pregnancies based on various surgical indications. However, ultrasonographically indicated cervical cerclage did not improve perinatal outcomes for twin pregnancies with cervical lengths < 25 mm. In contrast, emergency transvaginal cerclage extended the duration of pregnancy by a median difference of approximately 10 weeks, significantly reduced the risk of spontaneous preterm birth before 32 weeks, and decreased neonatal mortality. Additionally, emergency cervical cerclage delayed delivery, regardless of whether cervical dilation was ≤ 1 cm or > 1 cm.
The distinction between emergency and ultrasound-indicated cerclage may reflect the timing and urgency of intervention. Emergency cerclage is often performed in response to acute conditions, such as significant cervical dilation or the presence of prolapsed membranes, where immediate action is necessary to prolong pregnancy. This timely intervention can help stabilize the pregnancy and mitigate risks associated with preterm labor, resulting in improved perinatal outcomes. Conversely, ultrasound-indicated cerclage is typically performed based on diagnostic imaging findings, which may not always represent an immediate threat to the pregnancy. As a result, this type of cerclage may not provide the same degree of benefit as emergency cerclage, particularly in terms of prolonging gestation and reducing neonatal complications.
There is limited evidence regarding the effectiveness of cervical cerclage in twin pregnancies with cervical insufficiency, and the available findings are somewhat conflicting. Some studies suggest that ultrasonographically indicated cerclage can significantly prolong gestation and reduce the rate of preterm birth before 34 weeks, especially when the cervical length is ≤ 15 mm. This procedure has also been associated with a decreased rate of neonatal intensive care unit admission18. For instance, a systematic review reported that cerclage increases gestation by an average of 2.89 weeks when the cervical length is < 15 mm, thereby reducing the risk of preterm birth (relative risk = 0.86, 95% confidence interval 0.74–0.99)14. Another study found that the incidence of preterm birth before 32, 34, and 37 weeks was lower in the cerclage group compared to the control group when cervical length was < 15 mm15. However, other research has suggested that ultrasonographically indicated cerclage may not improve neonatal outcomes in twin pregnancies10,11. In our study, we observed that ultrasonographically indicated cerclage did not result in improved outcomes, which aligns with some of these findings. This discrepancy between studies suggests that the effectiveness of ultrasound-indicated cerclage in twin pregnancies remains uncertain and requires further investigation to clarify its potential benefits and limitations.
A systematic review showed that cervical cerclage prolongs gestation by 6.78 weeks and reduces the risk of preterm birth before 34 weeks in twin pregnancies with cervical dilation > 1 cm, supporting the use of emergency cerclage14. Additionally, a recent randomized controlled trial also demonstrated that emergency cerclage, as indicated by a physical examination, significantly reduces preterm birth before 28 weeks and neonatal mortality in twin pregnancies with painless cervical dilatation of 1–5 cm at 24 weeks gestation19. These findings suggest that cervical cerclage significantly reduces the rate of preterm birth in twin pregnancies with cervical dilatation > 1 cm. Specifically, emergency cerclage was found to prolong pregnancy by 5–7 weeks compared to expectant management in these women20,21. Consistent with our results, emergency cervical cerclage improved perinatal outcomes in twin pregnancies.
Although some data suggest that history-indicated cervical cerclage may be beneficial for twin pregnancies22, this finding has not been consistently supported by other studies9. In our study, ultrasounds were conducted at 12 weeks, which is earlier than the usual practice1, for pregnant women with a history of cervical surgery, preterm labor, or second-trimester miscarriage. However, our study did not include history-indicated cervical cerclage, highlighting the need for future studies to provide more definitive evidence.
In previous studies, cervical cerclage has been indicated for twin pregnancies between 16 and 24 weeks of gestation14,15. In the present study, the overall median gestational age at the time of the procedure was 21 weeks. However, the timing of the procedure varies according to specific indications. The median gestational age for ultrasound-indicated cervical cerclage was 16 weeks, whereas the median age for emergency cervical cerclage was 23 weeks. Therefore, the timing of the procedure is largely dependent on the indication, highlighting the need for further research.
One strength of this study is the homogeneity achieved by having all patients followed by the same multidisciplinary team, with standardized cervical cerclage procedures and medical treatments applied, thus reducing potential operator-dependent biases. However, as a retrospective cohort study, there is a possibility of information bias, as the medical records may not fully capture all relevant conditions at the time of treatment. This highlights the need for future randomized controlled trials to verify our findings.
Recent studies have proposed alternative cerclage methods, such as laparoscopic cerclage and surgical robot-assisted cerclage23–26. However, most of these procedures are performed in singleton pregnancies, and more robust evidence for twin pregnancies is needed. Our study exclusively focused on the more commonly used transvaginal cerclage, and other surgical methods were not explored, which may represent a potential limitation of this study.
Another important limitation of our study is the exclusion of 3 participants due to loss to follow-up. Although no formal sensitivity analysis was conducted, the proportion of these exclusions was small (1.5%), and their exclusion is unlikely to have significantly affected the overall findings.
Nevertheless, selection bias, particularly in the allocation of patients to cerclage and non-cerclage groups, should be considered. The decision to perform cerclage was likely influenced by clinical factors such as gestational age, cervical length, and dilation, which may have introduced bias by indication. Despite employing various methods to balance baseline characteristics, the existing differences may still have influenced the results. Furthermore, the limited sample size may have affected the findings, especially within the ultrasonographically indicated cerclage group. Future studies with larger cohorts and extended follow-up periods are necessary to confirm these results.
Conclusion
In this study, we investigated transvaginal cerclage in twin pregnancies, distinguishing between various indications for its use. Overall, cervical cerclage was found to improve the prognosis of twin pregnancies under specific conditions. Notably, while ultrasonographically indicated cerclage did not significantly enhance pregnancy outcomes, emergency cerclage may effectively prolong gestation, reduce the risk of spontaneous preterm birth before 32 weeks, and lower neonatal mortality, thereby improving perinatal prognosis. However, due to differences in gestational age and cervical condition at diagnosis between the cerclage and non-cerclage groups, these results should be interpreted with caution.
Author contributions
Conceptualization, Jiahao Zhu and Weishe Zhang; Data curation, Jiahao Zhu; Formal analysis, Jiahao Zhu, Yi Huang and Jingrui Huang; Funding acquisition, Weishe Zhang and Jingrui Huang; Investigation, Jiahao Zhu; Methodology, Jiahao Zhu, Jingrui Huang; Resources, Yi Huang, Hongtao Zeng, Weishe Zhang; Writing—original draft, Jiahao Zhu; Writing—review and editing Jingrui Huang.
Funding
This research was funded by the Natural Science Foundation of Hunan Province (2022JJ40789), the National Natural Science Foundation of China (82301927, 82371700, 81974236, 81571516), the Major Scientific and Technological Projects for Collaborative Prevention and Control of Birth Defects in Hunan Province (2019SK1010, 2019SK1015), the Key Research and Development Program of Hunan Province (2020SK2072).
Data availability
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.
Declarations
Ethics approval and consent to participate
Data on the perioperative surgical conditions and outcomes were collected. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institution, and informed consent was obtained. The study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the Medical Ethics Committee of the hospital (202112275).
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Contributor Information
Jingrui Huang, Email: jingruihuang@hotmail.com, Email: huangjingrui@csu.edu.cn.
Weishe Zhang, Email: zhangweishe@yeah.net.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.