Pre-pregnancy blood pressure and pregnancy outcomes: a nationwide population-based study

Association of pre-/early pregnancy high blood pressure and pregnancy outcomes: a systemic review and meta-analysis

BACKGROUND

Maternal high blood pressure (BP) was associated with adverse pregnancy outcomes. This study aimed to synthesize evidence on the association between high BP prior to or in early pregnancy with maternal and fetal complications.

METHODS

We searched the cohort studies assessing the effect of high BP in the Medline, Embase, Web of Science and China National Knowledge Internet databases. A random-effects model was used to estimate the pooled odds ratios (ORs) with 95% confidence intervals (CIs). The protocol was registered in PROSPERRO (CRD 42023414945).

RESULTS

23 eligible studies were identified. High BP prior to or in early pregnancy was associated with higher odds of hypertensive disorders of pregnancy (OR 2.90, 95% CI 1.91-3.89), gestational hypertension (2.56, 2.01-3.12), preeclampsia (3.20, 2.66-3.74), gestational diabetes mellitus (1.71, 1.36-2.06), preterm birth (1.66, 1.39-1.93), stillbirth (2.01, 1.45-2.58) and neonatal intensive care unit admission (1.22, 1.08-1.37). Subgroup analyses indicated that pre-hypertension could significantly increase the odds of these outcomes except for stillbirth, though the odds were lower than hypertension.

CONCLUSIONS

High BP prior to or in early pregnancy was associated with adverse pregnancy outcomes and this association increased with hypertension severity. The findings emphasized an urgent need for heightened surveillance for maternal BP, especially pre-hypertensive status.

Preconception Blood Pressure and Adverse Pregnancy Outcomes: A Population-Based Cohort Study

BACKGROUND

Adverse pregnancy outcomes (APOs) share clinical features and risk factors with cardiovascular disease and there is an increasing prevalence of hypertension among reproductive women. However, the associations between maternal preconception blood pressure (BP) and APOs remain controversial and inconclusive.

METHODS

This population-based cohort study used data of 567 127 mother-neonate-father triads from the National Free Preconception Checkup Project in Guangdong Province, China. Maternal BP levels within 1 year before pregnancy were classified using the American College of Obstetricians and Gynecologists definition of hypertension. The primary outcome was a composite of APOs, including preterm birth, small for gestational age, and perinatal infant death. Log-binomial and marginal structural binomial regressions were employed to estimate adjusted risk ratios and absolute risk differences, respectively.

RESULTS

Compared with women with normal BP, women with elevated BP (adjusted risk ratio, 1.07 [95% CI, 1.05-1.09]; absolute risk difference, 1.03% [95% CI, 0.72%-1.29%]), hypertension (adjusted risk ratio, 1.25 [95% CI, 1.18-1.32]; and absolute risk difference, 3.42% [95% CI, 1.97%-5.42%]) had a higher risk of a composite of APOs. Compared with women with normal BP, women with elevated BP and hypertension had higher risks of multiple APOs, preterm birth, small for gestational age, and perinatal infant death. However, these associations attenuated with increasing duration of pregnancy preparation and were not statistically significant beyond 90 days of pregnancy preparation.

CONCLUSIONS

Women with elevated BP or hypertension before pregnancy were associated with an increased risk of APOs. Preconception hypertension screening and control among women should not be ignored by policymakers, clinicians, and the general population.

Association of maternal preconception blood pressure with preterm birth: a population-based cohort study

The association between maternal preconception blood pressure (BP) and preterm birth (PTB) is still unclear. The purpose of this study was to investigate the association between maternal preconception BP and PTB. This population-based cohort study included 715 984 Chinese women aged 20-49 years who participated in the National Free Preconception Health Examination Project and successfully had a singleton livebirth during 2014-2019 in Guangdong Province, China. Maternal preconception BP were measured by trained health workers. Multivariate logistic regression models and restricted cubic spline regressions were used to examine the association and dose-response relationship between maternal preconception BP and PTB, respectively. Maternal preconception hypertension was associated with the increased risk of PTB (adjusted odds ratios (aOR): 1.24; 95% CI: 1.14-1.34). Compared to women with normal preconception BP, the aORs for PTB were 1.09 (95% CI: 1.06-1.12), 1.24 (95% CI: 1.13-1.36), and 1.43 (95% CI: 1.15-1.79) for women with preconception elevated BP (120-139/ 80-89 mmHg, stage-1 hypertension (140-159/ 90-99 mmHg, and stage-2 hypertension (160-179/100-109 mmHg), respectively. According to the 2017 American College of Cardiology/American Heart Association criteria, maternal preconception elevated BP and hypertension were also significantly associated with an increased risk of PTB. Preconception systolic and diastolic BP showed a U-shaped (χ2 = 40.54; nonlinear P < 0.001) and linear (χ2 = 6.62; nonlinear P = 0.085) dose-response relationship with PTB, respectively. The association was modified by maternal age and preconception body mass index. These findings identify maternal preconception elevated BP and hypertension as a modifiable risk factor for PTB, providing evidence for future research studies, public health and clinical interventions.

Reducing the Rate of Premature Births through Early Diagnosis and Pregnancy-Adapted Treatment of Hypothyroidism

Introduction

The aim of this study was to determine the extent to which regular monitoring of maternal free thyroxine level and pregnancy-adapted L-thyroxine replacement therapy before and during pregnancy in patients with existing or newly diagnosed latent and manifest hypothyroidism as well as hypothyroxinemia can influence the rate of premature births.

Materials and Methods

This is a retrospective cohort study assessing 1440 pseudonymized survey questionnaires to evaluate the risks of premature birth with two study groups from the same medical practice, and a nationally recruited control group. Study group A (n = 360) had already been taking L-thyroxine prior to conception, study group B (n = 580) started taking it after conception. Both study groups had a maximum gestational age of 12 + 0 GW. In the study groups, TSH and free thyroxine levels were determined regularly for dose adjustment purposes. The aim was to keep the free thyroxine level in the euthyroid hyperthyroxinemic range within the pregnancy adapted reference range. The control group (n = 500) had taken L-thyroxine during pregnancy according to criteria that were not known, as the questionnaire did not include any questions regarding this matter. Taking other risk factors into account, the influence of pregnancy-adapted L-thyroxine replacement therapy on the rate of premature births was determined using logistic regression analysis.

Results

Compared with the control group, the premature birth rate was 70% lower (p < 0.0001) in study group A and 42% lower in study group B (p = 0.0086), while the odds ratio, at 3.46, was particularly significant in study group A. High blood pressure (odds ratio 5.21), body mass index per kg/m 2 (odds ratio 0.91) and S. p. premature birth were identified as other independent risk factors.

Conclusion

The results show an association between more intensive thyroid diagnostics and pregnancy-adapted L-thyroxine replacement therapy and a decrease in premature births. Further studies should be conducted to confirm these results.

Pregnancy Outcomes in Females with Stage 1 Hypertension and Elevated Blood Pressure Undergoing In Vitro Fertilization and Embryo Transfer

Objective: To determine whether stage 1 hypertension and elevated blood pressure (BP), as defined by the 2017 American College of Cardiology/American Heart Association (ACC/AHA) guidelines, prior to pregnancy contributes to adverse pregnancy outcomes in females who conceived by in vitro fertilization and embryo transfer (IVF-ET). Methods: This retrospective cohort study involved 2239 females who conceived by IVF-ET and delivered live neonates. BPs recorded before IVF-ET were collected. Elevated BP was defined as at least two systolic BPs of 120 to 129 mmHg. Stage 1 hypertension was defined as at least two systolic BPs of 130 to 139 mmHg or diastolic BPs of 80 to 89 mmHg. Results: Among the females included in this study, 18.5% (415/2239) had elevated BP and 10.0% (223/2239) had stage 1 hypertension. Multiple logistic regression analysis showed that females with stage 1 hypertension had higher risks of hypertensive disorders in pregnancy (HDP) [adjusted odds ratio (aOR) 1.65; 95% confidence interval (CI) 1.16-2.35] and preeclampsia (aOR 1.52; 95% CI 1.02-2.26) than normotensive females. However, the risks of HDP (aOR 0.88; 95% CI 0.64-1.21) and preeclampsia (aOR 0.83; 95% CI, 0.57-1.20) in females with elevated BP were not significantly different from those in normotensive females. The females were then categorized into five groups by systolic and diastolic BP; females with systolic BP of 130 to 139 mmHg or diastolic BP of 85 to 89 mmHg had significantly increased risks of HDP and preeclampsia. Conclusion: Stage 1 hypertension before IVF-ET was an independent risk factor for HDP and preeclampsia.