Prevalence of newly diagnosed essential hypertension within one year postpartum: a systematic review and meta-analysis

Abstract

Objective

Pregnancy induces a state of cardiovascular stress and can lead to long-lasting effects irrespective of complications in pregnancy. However, the magnitude of these effects needs to be clarified. This study seeks to determine the prevalence of newly diagnosed essential hypertension within one year postpartum among the obstetric population who experienced uncomplicated pregnancies.

Data sources

A comprehensive search of the databases MEDLINE, Cochrane Central Register of Controlled Clinical Trials, EMBASE, Web of Science, and CINAHL was conducted for studies published up to March 2023.

Study eligibility criteria

Studies that assessed healthy individuals between 12 weeks and one year postpartum with newly diagnosed essential hypertension (≥140/90) and without pregnancy complications were included. Case studies, systematic reviews, and meta-analyses were excluded, along with studies involving pregnant patients who were either less than three months or more than one year postpartum, those with pre-existing hypertension or pregnancy complications, or those with pre-existing medical conditions.

Study appraisal and synthesis methods

Meta-analyses using random-effects models calculated pooled prevalence estimates and examined mean arterial pressure, systolic blood pressure, and diastolic blood pressure. Subgroup analyses considered the timing of blood pressure assessment, geographical location, and the presence of interventions.

Results

In eight studies with 3070 participants, the prevalence of newly diagnosed hypertension was 2.96% (95% confidence interval [CI], 1.15%–7.43%; I², 80%). No significant differences were observed in the subgroup analyses. Across 30 studies with 1782 individuals, the average systolic blood pressure was 109.88 mmHg (95% CI, 108–111.75; I², 92.2%), and diastolic blood pressure was 70.99 mmHg (95% CI, 68.84–73.14; I², 95.7%). In 12 studies with 339 individuals, the average mean arterial pressure was 82.01 mmHg (95% CI, 79.84–84.19; I², 93.6%).

Conclusions

These findings suggest that nearly 3 in 100 healthy individuals with uncomplicated pregnancies are diagnosed with de novo essential hypertension within one year postpartum. This underscores the need to extend cardiovascular screening to all postpartum individuals for one year, regardless of medical or pregnancy history.

AJOG Global Reports at a Glance.

Why was this study conducted?

This study aimed to determine the prevalence of newly diagnosed essential hypertension within one year postpartum among women who had uncomplicated pregnancies, recognizing that pregnancy induces cardiovascular stress with lasting effects, even in the absence of complications.

Key findings?

Three out of every 100 individuals with uncomplicated pregnancies are diagnosed with de novo hypertension within one year postpartum.

What does this add to what is known?

While previous studies have shown that healthy women with normotensive pregnancies may have a lower risk of future cardiovascular disease compared to those with complications in pregnancy or medical comorbidities, this risk is not negligible.

Introduction

Cardiovascular disease (CVD) is the leading cause of death among women globally,¹ driving significant efforts to identify those at risk as early as possible. In women, the onset of signs and symptoms arises insidiously and often presents atypically compared to men, which leads to misdiagnoses.² Pregnancy serves as a cardiovascular stress test with hemodynamic alterations that unmask vulnerabilities to future CVD.^3,4 This period presents a critical window for identifying women at risk and implementing early interventions and lifestyle modifications, as up to 80% of CVD cases are preventable.² It is well established that pregnancy complications, such as hypertensive disorders of pregnancy, gestational diabetes, intrauterine growth restriction, and placental abruption, are associated with a 1.5 to 4-fold increased risk of future CVD.4, 5, 6^,7 Specifically, hypertensive disorders of pregnancy, which affect 10% of pregnancies, significantly increase the likelihood of developing new chronic hypertension (HTN) within 6 to 12 months postpartum, as well as the risk of metabolic syndrome and elevated blood glucose levels.^8,9 National guidelines from the United States, United Kingdom, Norway, Canada, and the Netherlands recommend blood pressure monitoring after hypertensive disorders of pregnancy.10, 11, 12, 13, 14, 15^,16 Both the American Heart Association (AHA) and the American College of Obstetricians and Gynecologists advise a CVD assessment 6 to 12 months postpartum for women with these disorders.17, 18, 19^,20

While chronic HTN can persist after a pregnancy complicated by HTN, it can also develop de novo following a normotensive pregnancy.²¹ However, the risk of CVD in postpartum women without a prior history of disease, family history of CVD, or pregnancy complications remains unclear. Recent evidence suggests that even healthy women without hypertensive disorders of pregnancy can experience new-onset HTN within one year postpartum, with incidence rates of 12.1% for blood pressure levels above 140/90 mmHg and 22% to 23.5% for levels above 130/80 mmHg.^8,21,22 These findings suggest that 1 in 5 women will develop HTN after the standard 6-week postpartum follow-up period has ended.²¹ The risk was notably elevated among Black women, those aged 35 or older, those who had a caesarean section, and current or former smokers.²¹ These results indicate that even healthy women with uncomplicated pregnancies may still be at considerable risk of future CVD, raising the question of whether postpartum screening should be extended to all individuals at one year postpartum.

This systematic review and meta-analysis aims to estimate the prevalence of newly diagnosed essential HTN within one year postpartum among the obstetric population who did not experience pregnancy complications. We hypothesized that these patients would exhibit relatively high levels of newly diagnosed essential HTN within one year postpartum, providing further support to expand screening guidelines to include all postpartum individuals, regardless of their medical or pregnancy history.

Materials and methods

Eligibility criteria

The study was registered in PROSPERO (ID: CRD42023469662). Essential HTN was defined as idiopathic or primary HTN without identifiable secondary causes. Prevalent HTN was defined as someone newly diagnosed in the postpartum period with no history of HTN. The AHA guidelines were used, which define HTN as a systolic blood pressure (SBP) ≥ 140 and/or a diastolic blood pressure (DBP) ≥ 90 mmHg. Inclusion criteria comprised studies involving pregnant people between 3 months (12 weeks) and one year postpartum with newly diagnosed essential HTN. Exclusion criteria included (1) pregnant patients less than three months or more than one year postpartum; (2) pregnant patients with pre-existing HTN or pregnancy complications; (3) patients with pre-existing medical comorbidities; (4) case studies or reports; and (4) systematic reviews or meta-analyses. Studies published up to March 2023 were considered.

Information sources and search strategy

The authors developed the search strategy in collaboration with a health sciences librarian. Relevant studies were identified using Medline, Cochrane, Web of Science, CINAHL, and Preprint Citation Index databases. MeSH terms included: (“hypertension” or “essential hypertension” or “high blood pressure” or “elevated blood pressure” or “abnormal blood pressure”) and (“Postpartum Period” or “postpartum” or “puerperium” or “postpartal” or “postnatal” or “postdelivery” or “after giving birth”) (Table A.1).

Table A.1.

Search strategy using Ovid Medline of data published up to and including March 2023.

#	Query
1	Postpartum Period/
2	puerperium.mp. [mp=title, book title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word]
3	postpartum.mp. [mp=title, book title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word]
4	postpartum.mp. [mp=title, book title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word]
5	postnatal.mp. [mp=title, book title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word]
6	postnatal.mp. [mp=title, book title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word]
7	postpartal.mp. [mp=title, book title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word]
8	postpartal.mp. [mp=title, book title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word]
9	postdelivery.mp. [mp=title, book title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word]
10	postdelivery.mp. [mp=title, book title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word]
11	after giving birth.mp. [mp=title, book title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word]
12	1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11
13	hypertension/ or essential hypertension/
14	hypertension.ab,kf,kw,ti.
15	high blood pressure.mp. [mp=title, book title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word]
16	elevated blood pressure.mp. [mp=title, book title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word]
17	abnormal blood pressure.mp. [mp=title, book title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word]
18	(increas* adj1 blood pressure).mp. [mp=title, book title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word]
19	13 or 14 or 15 or 16 or 17 or 18
20	12 and 19
21	limit 20 to (editorial or "review")
22	20 not 21

Study selection and assessment of risk of bias

Covidence software was used to export abstracts, eliminate duplicates, and screen studies. A team of four reviewers worked on screening (JK, AM, JP, KK). At each stage of screening, two reviewers independently screened titles, abstracts and full text for inclusion and exclusion criteria. Disagreements were resolved by a third reviewer. Two independent reviewers completed a quality assessment of included studies using the Joanna Briggs Institute's critical appraisal Checklist for Prevalence Studies.²³ A third independent reviewer resolved disagreements. Studies were classified as having a low, medium, or high risk of bias.

Data extraction

Data extraction was carried out by two team members using a preformed worksheet developed by the research team. Information regarding study characteristics, baseline demographics of study samples, method of outcome measurement, prevalence estimates, and blood pressure values were extracted. Any discrepancy between reviewers was resolved through discussion and consensus, with input from a third reviewer.

Data synthesis

Meta-analyses were performed using random-effects models to calculate pooled prevalence estimates of newly diagnosed HTN, SBP, DBP, and mean arterial pressure (MAP), with 95% confidence intervals (CI). Forest plots were generated to present these results visually. Heterogeneity was assessed using an I² estimate. Subgroup analyses were performed according to time of assessment (less or greater than six months postpartum), geographical location (North America vs other), and interventions to identify potential confounding factors. All analyses were conducted using the "meta" package and R version 4.2.0.

Results

Study selection and characteristics

Title and abstract screening were completed for 9922 studies, leading to a full-text review of 269 studies. Thirty-nine studies met the criteria for inclusion (Figure 1). A summary of these studies is presented in Table 1. Thirty-five of the studies were prospective cohort studies, two were retrospective cohort studies, and two were follow-up studies of randomized controlled trials. The quality assessment for each study is illustrated in Table 2. Primary sources of potential bias included inadequate sample size, study subjects and/or setting not described in detail, inappropriate sample frame to address the target population, and inadequate response rate.

Figure 1.

Preferred reporting items for systematic reviews and meta-analyses flow diagram of search strategy and results.

Kaminker et al. Prevalence of newly diagnosed essential hypertension within one year postpartum. Am J Obstet Gynecol 2025.

Table 1.

Summary of study characteristics. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) are all reported as mean ± SD.

	Origin	Study Type	Timing of postpartum assessment (months)	Intervention	Prevalence	SBP (mmHg)	DBP (mmHg)	MAP (mmHg)
Ackerman-Banks et al (2023)	USA, Canada	Prospective cohort study	6–12	No	3.2	N/A	N/A	N/A
Agatisa et al (2004)	USA	Prospective cohort study	6–12	Yes	N/A	105 ± 7.5	62 ± 3.74	77 ± 3.74
Akhter et al (2013)	Sweden	Prospective cohort study	12	No	N/A	111 ± 7	69 ± 8	N/A
Andreas et al (2016)	Austria	Prospective cohort study	6	No	N/A	106 ± 7	74 ± 7	N/A
Barden et al (1999)	Australia	Retrospective cohort study	6	No	N/A	107 ± 9.16	65 ± 9.17	N/A
Bergman et al (2016)	Sweden	Prospective cohort study	12	No	N/A	110 ± 6	68 ± 7	82 ± 7
Blaauw et al (2005)	The Netherlands	Prospective cohort study	3–11	No	N/A	113 ± 9	68 ± 7	N/A
Di Martino et al (2023)	Italy	Prospective cohort study	6–10	No	N/A	N/A	N/A	82.9 ± 8.4
Ehrenthal et al (2014)	USA	Prospective cohort study	12	No	2.4	111.1 ± 9.7	72.9 ± 7.4	86.4 ± 8.9
El Mokadem et al (2021)	Egypt	Prospective cohort study	3	No	N/A	113 ± 9.9	72.9 ± 8	N/A
Estensen et al (2013)	Norway	Prospective cohort study	6	No	N/A	110 ± 9	66 ± 8	86 ± 7
Filippi et al (2010)	UK, Benin, Sweden	Prospective cohort study	12	No	0.7	N/A	N/A	N/A
Fischer et al (2000)	Germany	Prospective cohort study	4–6	Yes	N/A	N/A	N/A	85.6 ± 9.7
Garnæs et al (2018)	Norway	Secondary analysis of a randomized controlled trial	3	Yes	8.8	124 ± 10.41	78.4 ± 8.04	N/A
Guilleminault et al (2000)	USA	Prospective cohort study	3	No	N/A	110 ± 9	74 ± 7	N/A
Hatton et al (2003)	USA	Follow up to a randomized controlled trial	3	Yes	N/A	103.6 ± 11	65.4 ± 8.9	N/A
Hillman et al (2017)	UK	Prospective cohort study	4.4–9.4	No	N/A	109.1 ± 7.9	63.9 ± 7.68	N/A
Ishaku et al (2021)	The Netherlands, Nigeria, UK, USA	Prospective cohort study	12	No	N/A	112.07 ± 13.8	72.55 ± 11.52	N/A
Janzarik et al (2019)	Germany, UK	Prospective cohort study	6	No	N/A	N/A	N/A	81.9 ± 7.8
Jesuino et al (2020)	Brazil	Prospective cohort study	3–5	Yes	0	N/A	N/A	N/A
Karkkainen et al (2014)	Finland	Prospective cohort study	3	No	N/A	104 ± 8	70 ± 6	N/A
Kennedy et al (2022)	Australia	Prospective cohort study	6	No	N/A	105 ± 10	67 ± 8
Lackner et al (2018)	Austria, Slovenia	Prospective cohort study	3.75–4.25	Yes	N/A	107.1 ± 9.3	68.9 ± 8.1	N/A
Mahendru et al (2014)	UK, Belgium	Prospective cohort study	3.5–4.25	No	N/A	104 ± 8	69 ± 6	82 ± 7
Meah et al (2021)	UK, USA	Prospective cohort study	3–4	Yes	N/A	105 ± 6	61 ± 4	75 ± 4
Moe et al (2020)	Norway, Germany	Prospective cohort study	12	No	0	N/A	N/A	N/A
Murphy et al (2015)	Canada	Prospective cohort study	6	No	N/A	106.5 ± 8.5	70.4 ± 4	N/A
Osoti et al (2020)	USA, Kenya	Prospective cohort study	6	No	N/A	122 ± 17.1	81.5 ± 12.4	N/A
Parker et al (2023)	USA	Retrospective cohort study	12	No	12.1	N/A	N/A	N/A
Raza et al (2019)	UK	Prospective cohort study	12	Yes	N/A	Arm 1 103.63 ± 41.04 Arm 2 138.68 ± 46.41	Arm 1 75.29 ± 36.97 Arm 2 91.91 ± 29.15	N/A
Scholten et al (2014)	The Netherlands, UK	Prospective cohort study	6–12	Yes	N/A	109 ± 6	66 ± 6	78 ± 5
Smith et al (2009)	Canada	Prospective cohort study	12	No	N/A	111.3 ± 9.3	72.7 ± 8.1	N/A
Soma-Pillary et al (2018)	South Africa	Prospective cohort study	12	No	N/A	115.08 ± 9.89	82.45 ± 9.16	N/A
Spaanderman et al (2000)	The Netherlands	Prospective cohort study	≥5	No	N/A	N/A	N/A	84 ± 8
Stanheiwcz et al (2017)	USA	Prospective cohort study	12	Yes	N/A	113 ± 6.93	72 ± 3.46	85 ± 1
Suntio et al (2010)	Finland	Prospective cohort study	3	No	N/A	104 ± 8	70 ± 6	N/A
Tyldum et al (2012)	Norway	Prospective cohort study	3	No	N/A	109 ± 7	71 ± 6	N/A
Veerbeek et al (2013)	The Netherlands	Prospective cohort study	6–9	No	N/A	115 ± 13.6	75 ± 13.6	N/A
Ziesler et al (2021)	Norway	Prospective cohort study	12	No	0	N/A	N/A	N/A

Kaminker et al. Prevalence of newly diagnosed essential hypertension within one year postpartum. Am J Obstet Gynecol 2025.

Table 2.

Quality assessments of individual studies using the JBI checklist.

Kaminker et al. Prevalence of newly diagnosed essential hypertension within one year postpartum. Am J Obstet Gynecol 2025.

Synthesis of results

In a pooled analysis of 8 studies with 3070 individuals, the prevalence of newly diagnosed HTN between 3 and 12 months postpartum was 2.96% (95% CI, 1.15%–7.43%; I², 80%) (Figure 2A). The relationship between sample size and hypertension prevalence estimates was plotted to assess whether larger studies tended to produce more extreme results. No clear trend was observed between sample size and prevalence estimates for MAP, SBP, or DBP. However, for the hypertension prevalence outcome, one study (Parker et al, 2023) was identified as an outlier with a much higher estimate than the other studies included in the analysis. We conducted a sensitivity analysis excluding this study from the meta-analysis. The overall hypertension prevalence estimate with this study included was 2.96 (95% CI 1.15, 7.43), while excluding the study reduced the estimate to 2.12 (95% CI 0.85, 5.20). This suggests that the Parker et al, 2023 study may have had an influence on the pooled estimate, and its exclusion provided a more conservative result. Subgroup analyses revealed that the prevalence of newly diagnosed HTN was higher in individuals 3 to 6 months postpartum than individuals 6 to 12 months postpartum (Figure 2B). Moreover, a higher prevalence was detected in North American studies relative to studies in other regions (Figure 2C). The prevalence was also greater in studies with interventions compared to studies without interventions (Figure 2D). However, overall, no significant difference in prevalence existed between any of the subgroups.

Figure 2.

Forest plots of newly diagnosed essential HTN prevalence within one year postpartum. A, Overall prevalence of 2.96% (k = 8, n = 3070). Subgroup analyses include: B, timing of assessment between 3 and 6 months (k = 2, n = 59) or 6 to 12 months postpartum (k = 6, n = 3011), C, study origin in North America (k = 3, n = 2569) or elsewhere (k = 5, n = 501), D, study involved an intervention (k = 2, n = 59) or not (k = 6, n = 3011) Prevalence estimates did not differ significantly between the subgroup analyses as indicated by overlapping CIs.

Kaminker et al. Prevalence of newly diagnosed essential hypertension within one year postpartum. Am J Obstet Gynecol 2025.

The average SBP and DBP were calculated across 30 studies with 1782 individuals. The mean SBP was 109.88 mmHg (95% CI, 108–111.75; I², 92.2%) and the mean DBP was 70.99 mmHg (95% CI, 68.84–73.14; I², 95.7%) (Figures 3A and 4A). The mean SBP and DBP showed no significant variation between subgroups based on the timing of assessment, geographic location, or intervention (Figures 3B–D and 4B–D).

Figure 3.

Forest plots of the mean SBP. A, The overall mean SBP was (k = 30, n = 1782). Subgroup analyses include: B, timing of assessment between 3 and 6 months (k = 16, n = 1143) or 6 to 12 months postpartum (k = 14, n = 639), C, study origin in North America (k = 7, n = 563) or elsewhere (k = 23, n = 1219), D, study involved an intervention (k = 9, n = 405) or not (k = 21, n = 1377). As indicated by overlapping CIs, SBP estimates did not differ significantly between the subgroup analyses.

Kaminker et al. Prevalence of newly diagnosed essential hypertension within one year postpartum. Am J Obstet Gynecol 2025.

Figure 4.

Forest plots of the mean DBP. A, The overall mean DBP was (k = 30, n = 1782). Subgroup analyses include: B, timing of assessment between 3 and 6 months (k = 16, n = 1143) or 6–12 months postpartum (k = 14, n = 639), C, study origin in North America (k = 7, n = 563) or elsewhere (k = 23, n = 1219), D, study involved an intervention (k = 9, n = 405) or not (k = 21, n = 1377). As indicated by overlapping CIs, DBP estimates did not differ significantly between the subgroup analyses.

Kaminker et al. Prevalence of newly diagnosed essential hypertension within one year postpartum. Am J Obstet Gynecol 2025.

The average MAP was 82.01 mmHg (95% CI 79.84–84.19; I², 93.6%) based on 12 studies with 339 individuals (Figure 5A). There were no significant differences in MAP among subgroups (Figures 5B–D).

Figure 5.

Forest plots of the MAP between studies. A, Overall MAP was 82.01 mmHg (k = 30, n = 1782). Subgroup analyses include: B, timing of assessment between 3 and 6 months (k = 16, n = 1143) or 6–12 months postpartum (k = 14, n = 639), C, study origin in North America (k = 7, n = 563) or elsewhere (k = 23, n = 1219), D, study involved an intervention (k = 9, n = 405) or not (k = 21, n = 1377). As indicated by overlapping CIs, MAP estimates did not differ significantly between the subgroup analyses.

Kaminker et al. Prevalence of newly diagnosed essential hypertension within one year postpartum. Am J Obstet Gynecol 2025.

Comment

Principal findings

Our results suggest that nearly 3 out of every 100 healthy individuals with uncomplicated pregnancies will develop newly diagnosed essential HTN within the first year postpartum. Although the risk appears to be higher within the first 6 months postpartum compared to the 6–12-month postpartum period, this difference was not statistically significant. The average blood pressure of approximately 110/71 mmHg and MAP of 82 mmHg were consistent between North American and non-North American populations and did not show significant variation when measured less than or greater than 6 months postpartum.

Results in the context of what is known

HTN remains the most prevalent risk factor for cardiovascular disease and the leading cause of death among women worldwide.²⁴ The age-standardized incidence of diagnosed hypertension in the general female population aged ≥20 years in Canada in 2007/08 was 2.3 per 100 persons per year.²⁵ Among women aged 20 to 44, the prevalence of hypertension was 19% with a blood pressure cutoff of ≥130/80, and 10% using the traditional ≥140/90 threshold.²⁶ Postpartum HTN, including in isolation, is one of the most important risk factors for the development of postpartum stroke.²⁷ Data on the necessity of HTN screening during the postpartum period for all women is limited, and even more so for those without a history of hypertensive disorders of pregnancy or pre-existing conditions.²⁷ The American College of Obstetricians and Gynecologists 2018 guidelines strongly endorse home blood pressure monitoring throughout pregnancy for all women, if financially feasible. However, there is limited evidence to support recommendations for postpartum blood pressure monitoring for healthy women.²³

According to current Hypertension Canada guidelines, HTN management and diagnosis are only considered up to 6 weeks postpartum for patients with CVD risk factors.²⁴ However, our findings indicate that even healthy patients may still be at a notable risk for de novo postpartum hypertension up to one year postpartum. The AHA acknowledges the risk posed to normotensive healthy women and endorses blood pressure evaluation for all women at 12 weeks postpartum, with no further follow-up if blood pressure is normalized at this time.²⁸ Consequently, the lack of identification of de novo postpartum HTN beyond 12 weeks may lead to delayed diagnosis and irreversible decline of existing pathophysiological damage secondary to long-term undiagnosed HTN in previously healthy, uncomplicated postpartum women.

The overall estimate of the prevalence of de novo hypertension in our study is lower than that reported in previous literature. This difference can be partly attributed to our use of the AHA’s guideline of ≥140/90 mmHg, which is stricter compared to the criteria of ≥130/80 mmHg used in other studies.^8,29 We used a cutoff of ≥140/90 mmHg which aligns with most of the existing literature. While there has been a recent shift toward a threshold of ≥130/80 mmHg, the body of data adopting this new cutoff remains limited. Our use of the higher threshold likely resulted in a more conservative estimate of prevalence, further underscoring how common postpartum hypertension is—even when using more stringent criteria. Additionally, differences in study duration and population characteristics may contribute to differences in prevalence. For example, Parker et al calculated an overall incidence of 22% for new-onset hypertension between 6 weeks and 12 months, capturing cases at an earlier time frame compared to our study’s minimum follow-up period of 12 weeks.²¹ Furthermore, our study excluded individuals with any prior health conditions or conditions that arose during pregnancy, whereas their criteria was less stringent as it included those with gestational diabetes.²¹

Although this study could not classify patients by race, previous research has shown that Black women have a slower decline in blood pressure than White women within North America leading to higher blood pressures at 6 weeks postpartum.³⁰ Black women with normotensive pregnancies have also been shown to have a 2.5-fold higher incidence of de novo hypertension compared to White women.³¹ North America represents a more culturally diverse population which may make it appear more similar to the non-North American group combined of populations from different geographic locations. Incorporating additional subgroups, such as race and socioeconomic status, may impact the distribution of results.

Current evidence for the monitoring of postpartum HTN complicated by preeclampsia is well documented. Giorgione et al (2020) provides a comprehensive systemic review and meta-analysis of current literature regarding the incidence of postpartum HTN within 2 years of a preeclamptic pregnancy.³² However, there is very minimal evidence regarding the general incidence of postpartum HTN. This review provides preliminary evidence supporting the need for extended postpartum hypertensive monitoring for all women. While studies have shown that patients with normotensive pregnancies have a lower risk of future CVD risk than those with hypertensive disorders of pregnancy,^33,34 their risk is not negligible. To date, data regarding de novo postpartum HTN in healthy women has largely been limited to control groups in studies focused on hypertensive disorders of pregnancy. This meta-analysis represents an initial effort to address this knowledge gap for the healthy, uncomplicated postpartum population, which comprises most clinical patients.²

Strengths and limitations

This systematic review, which includes a pooled meta-analysis of thirty-nine studies, was conducted using a comprehensive literature search across five well-established databases without geographical limitations. It is the first global systematic review and meta-analysis on this topic.

Limitations of this review include variability in study quality and heterogeneity in study designs and populations. To address these issues, we performed a quality assessment to exclude studies deemed to have a high risk of bias. Nonetheless, the quality assessment of included studies showed that only seven had an adequate sample size of over 100 participants, while the remaining 32 studies had a high risk of bias due to small sample sizes. These studies with smaller sample sizes may introduce bias by showing exaggerated effects compared to larger studies. We also used random effects models to account for variation in the true effect size of each study and mitigate the impact of heterogeneity.

Potential confounding factors, such as variation in populations, timing of postpartum blood pressure assessments, and the presence of interventions, were assessed through subgroup analyses which showed no significant differences between any subgroups tested. However, subgroup analysis by race or socioeconomic status (SES) was not feasible due to the limited reporting of race/ethnicity data across the included studies, which limits the generalizability of our findings. Prior research has consistently demonstrated racial and socioeconomic disparities in postpartum hypertension.^35,36,37 Specifically, Black, Indigenous, and low SES populations demonstrate a disproportionately higher risk of both short- and long-term hypertensive disorders following pregnancy.^35,36,37 This is likely due to multifactorial causes including biological susceptibility, systemic racism, healthcare access disparities, and other social determinants of health.^35,36,37 Without stratified data, we are unable to determine whether the pooled prevalence estimate identified in our study accurately reflects the risk among all racial groups, or whether it may underestimate the burden in higher-risk populations. Future research should prioritize standardized reporting of racial and socioeconomic demographics to allow for subgroup analyses to better understand the differential impact of postpartum hypertension. This is essential for informing equitable postpartum screening practices and addressing potential disparities in long-term cardiovascular outcomes.

Moreover, this review only included studies published in English. As a result, relevant studies in other languages may have been excluded, which could limit the generalizability of our findings beyond predominately English-speaking medical systems.

Conclusions and research implications

This review demonstrates the absence of guidelines for HTN screening beyond 12 weeks for healthy women with uncomplicated pregnancies. Our meta-analysis affirms the importance of screening for de novo HTN up to one year postpartum, with an incidence rate of 6.85% within the 3 to 6 month postpartum period and an overall rate of 2.96% within 1 year postpartum. Additional research is required to evaluate the clinical implications of new-onset hypertension to balance the prevention of future cardiovascular disease risk with considerations of cost, availability, and accessibility when extending screening guidelines. Future research should focus on developing a pilot program that includes HTN screening for all, to assess its clinical impact and may provide further support for our study with a more accurate estimate of HTN incidence.

CRediT authorship contribution statement

Jennifer D. Kaminker: Writing – original draft, Visualization, Methodology, Investigation, Data curation. Alexandra MacMaster: Writing – original draft, Methodology, Investigation. Jessica Pudwell: Writing – review & editing, Visualization, Methodology, Investigation, Formal analysis. Kira King: Investigation. Graeme N. Smith: Writing – review & editing, Supervision, Conceptualization.