Chronic hypertension and adverse pregnancy outcome: a cohort study

Hypertensive disorders in pregnancy and stillbirth rates: a facility-based study in China

Objective

To assess the association between hypertensive disorders in pregnancy and the stillbirth rate.

Methods

We obtained all data from China's National Maternal Near Miss Surveillance System for 2012 to 2016. Associations between hypertensive disorders in pregnancy and stillbirths, stratified by fetus number and gestational age, were assessed using Poisson regression analysis with a robust variance estimator.

Findings

For the period, 6 970 032 births, including 66 494 stillbirths, were reported to the surveillance system. The weighted stillbirth rate in women with a hypertensive disorder in pregnancy was 21.9 per 1000 births. The risk was higher in those who had received few antenatal care visits or who were poorly educated. For singleton pregnancies, the adjusted risk ratio (aRR) for a stillbirth among women with hypertensive disorders in pregnancy compared with normotensive women was 3.1 (95% confidence interval, CI: 2.85-3.37). The aRR for hypertensive disorder subtypes was: 6.66 (95% CI: 5.57-7.96) for superimposed preeclampsia; 4.15 (95% CI: 3.81-4.52) for preeclampsia or eclampsia; 2.32 (95% CI: 1.87-2.88) for chronic hypertension; and 1.21 (95% CI: 1.08-1.36) for gestational hypertension. For multiple pregnancies, the association between stillbirths and hypertensive disorders in pregnancy was not significant, except for superimposed preeclampsia (aRR: 1.95; 95% CI: 1.28-2.97).

Conclusion

To minimize the incidence of stillbirths, more attention should be paid to chronic hypertension and superimposed preeclampsia in singleton pregnancies and to superimposed preeclampsia in multiple pregnancies. Better quality antenatal care and improved guidelines are needed in China.

Chronic hypertension: first-trimester blood pressure control and likelihood of severe hypertension, preeclampsia, and small for gestational age

BACKGROUND

There is extensive evidence that prepregnancy chronic hypertension is associated with a high risk of development of severe hypertension and preeclampsia and birth of small-for-gestational-age neonates. However, previous studies have not reported whether antihypertensive use, blood pressure control, or normalization of blood pressure during early pregnancy influences the rates of these pregnancy complications.

OBJECTIVE

The purpose of this study was to stratify women with prepregnancy chronic hypertension according to the use of antihypertensive medications and level of blood pressure control at the first hospital visit during the first trimester of pregnancy and to examine the rates of severe hypertension, preeclampsia, and birth of small-for-gestational-age neonates according to such stratification.

STUDY DESIGN

We conducted a prospective study of 586 women with prepregnancy chronic hypertension, in the absence of renal or liver disease, that was booked at a dedicated clinic for the management of hypertension in pregnancy. The patients had singleton pregnancies and were subdivided according to findings in their first visit: group 1 (n=199), blood pressure <140/90 mm Hg without antihypertensive medication; group 2 (n=220), blood pressure <140/90 mm Hg with antihypertensive medication; and group 3 (n=167), systolic blood pressure ≥140 mm Hg and/or diastolic blood pressure ≥90 mm Hg, despite antihypertensive medication. In the subsequent management of these pregnancies, our policy was to maintain the blood pressure at 130-140/80-90 mm Hg with the use of antihypertensive medication; antihypertensive drugs were stopped if the blood pressure was persistently <130/80 mm Hg. The outcome measures were severe hypertension (systolic blood pressure ≥160 mm Hg and/or diastolic blood pressure ≥110 mm Hg), preterm and term preeclampsia (in addition to hypertension at least 1 of renal involvement, liver impairment, neurologic complications, or thrombocytopenia), and birth of small-for-gestational-age neonates (birthweight <5th percentile for gestational age). The incidence of these complications was compared in the 3 strata.

RESULTS

The median gestational age at presentation was 10.0 weeks (interquartile range, 9.1-11.0 weeks). In groups 2 and 3, compared with group 1, there was a significantly higher body mass index, incidence of black racial origin, and history of preeclampsia in a previous pregnancy. There was a significant increase from group 1 to group 3 in the incidence of severe hypertension (10.6%, 22.2%, and 52.1%), preterm preeclampsia with onset at <37 weeks of gestation (7.0%, 15.9%, and 20.4%), and small for gestational age (13.1%, 17.7%, and 21.1%), but not term preeclampsia with onset at ≥37 weeks of gestation (9.5%, 9.1%, and 6.6%).

CONCLUSIONS

In women with prepregnancy chronic hypertension, the rates of development of severe hypertension, preterm preeclampsia, and small for gestational age are related to the use of antihypertensive medications and the level of blood pressure control at the first hospital visit during the first trimester of pregnancy.

High normal blood pressure in early pregnancy also contribute to early onset preeclampsia and severe preeclampsia

OBJECTIVE

This study was to evaluate effects of high normal blood pressure (HNBP) in early pregnancy on total preeclampsia, early preeclampsia, and severe preeclampsia.

METHODS

We conducted a multicenter, national representative retrospective cohort study. HNBP was defined as systolic blood pressure between 130 and 140 mmHg or diastolic blood pressure between 85 and 90 mmHg. We used multivariable logistic regression to examine the associations of HNBP and the risks of above three types of preeclampsia.

RESULTS

We included 58 054 women who were normotensive and nulliparous in early pregnancy. 4 809 (8.3%) fulfilled the definition of having HNBP, 16 682 (28.7%) were in normal blood pressure group, and 36 563 (63.0%) were in optimal blood pressure group. The incidence rates of total preeclampsia, early preeclampsia, and severe preeclampsia were 2.1% (1 217), 0.8% (491), and 1.4% (814), respectively. Compared to having optimal blood pressure, women with HNBP had significantly higher odds of total preeclampsia (odds ratio (OR) = 4.028, 95% confidence interval (CI) 3.377, 4.804), severe preeclampsia (OR = 3.542, 95% CI 2.851, 4.400), and early preeclampsia (OR = 8.163, 95% CI 6.219, 10.715). Our restricted cubic spline results supported the dose-response relationship between continuous blood pressure and the odds ratio of three types of preeclampsia. The fraction of early preeclampsia associated with prehypertension was 58.6%, which was higher than those of total preeclampsia (42.2%) or severe preeclampsia (40.5%).

CONCLUSION

Women in early pregnancy with HNBP more likely develop total preeclampsia, early preeclampsia and severe preeclampsia, compared to those with optimal blood pressure. HNBP contribute more to early preeclampsia than severe preeclampsia. Our study provided robust epidemiological evidences for monitoring HNBP in early pregnancy to reduce the risks of preeclampsia.

Chronic hypertension: effect of blood pressure control on pregnancy outcome

OBJECTIVE

To examine whether in patients with CH and mild to moderate hypertension the level of control of blood pressure during pregnancy has a beneficial or adverse effect on the risk of PE or SGA.

METHODS

We performed a systematic review and meta-analysis of randomized controlled trials of patients with mild to moderate CH in pregnancy that reported the impact of different levels of control of blood pressure on the risk of PE or SGA. We completed a literature search through PubMed, Embase, Cinahl, Web of science, Cochrane CENTRAL Library Relative risks with random effect were calculated with their 95% confidence intervals (95%CI).

RESULTS

Six trials including 495 participants provided data on blood pressure (BP) after entry to the study. Four studies compared antihypertensive agents to no treatment and two studies compared antihypertensive agents to placebo. All trials were conducted between 1976 and 1990 and were considered to be at high risk of bias. There was high heterogeneity between studies for mean arterial pressure (MAP) after randomization (I² = 87%) and SGA (I² = 60%), but not for PE (I² = 0%). There were large differences between studies in the inclusion criteria, antihypertensive regimens, targets of therapy, and gestational age range at entry to the trials. In women receiving antihypertensive therapy, compared to those receiving placebo or no treatment, the MAP after entry to the trial was significantly lower (mean difference -4.2 mmHg, 95%CI -6.6 to -1.8; p = .006). However, there was no significant reduction in the risk of PE (relative risks (RR) 1.03, 95%CI 0.63-1.68; p = .90) or SGA (RR 1.01, 95%CI 0.35-2.93; p = .99).

CONCLUSIONS

The findings of the meta-analysis suggest that lowering the blood pressure by antihypertensive medication in women with mild to moderate hypertension in the context of CH has no significant effect on the risk of SGA or PE.

Aspirin for Evidence-Based Preeclampsia Prevention trial: effect of aspirin in prevention of preterm preeclampsia in subgroups of women according to their characteristics and medical and obstetrical history

BACKGROUND

The Combined Multimarker Screening and Randomized Patient Treatment with Aspirin for Evidence-Based Preeclampsia Prevention trial demonstrated that in women who were at high risk for preterm preeclampsia with delivery at <37 weeks' gestation identified by screening by means of an algorithm that combines maternal factors and biomarkers at 11-13 weeks' gestation, aspirin administration from 11 to 14 until 36 weeks' gestation was associated with a significant reduction in the incidence of preterm preeclampsia (odds ratio 0.38; 95% confidence interval, 0.20 to 0.74; P=0.004).

OBJECTIVE

We sought to examine whether there are differences in the effect of aspirin on the incidence of preterm preeclampsia in the Aspirin for Evidence-Based Preeclampsia Prevention trial in subgroups defined according to maternal characteristics and medical and obstetrical history.

STUDY DESIGN

This was a secondary analysis of data from the Aspirin for Evidence-Based Preeclampsia Prevention trial. Subgroup analysis was performed to assess evidence of differences in the effect of aspirin on incidence of preterm preeclampsia in subgroups defined by maternal age (<30 and ≥30 years), body mass index (<25 and ≥25 kg/m²), racial origin (Afro-Caribbean, Caucasian and other), method of conception (natural and assisted), cigarette smoking (smoker and non-smoker), family history of preterm preeclampsia (present and absent), obstetrical history (nulliparous, multiparous with previous preterm preeclampsia and multiparous without previous preterm preeclampsia), history of chronic hypertension (present and absent). Interaction tests were performed on the full data set of patients in the intention to treat population and on the data set of patients who took ≥ 90% of the prescribed medication. Results are presented as forest plot with P values for the interaction effects, group sizes, event counts and estimated odds ratios. We examined whether the test of interaction was significant at the 5% level with a Bonferroni adjustment for multiple comparisons.

RESULTS

There was no evidence of heterogeneity in the aspirin effect in subgroups defined according to maternal characteristics and obstetrical history. In participants with chronic hypertension preterm preeclampsia occurred in 10.2% (5/49) in the aspirin group and 8.2% (5/61) in the placebo group (adjusted odds ratio, 1.29; 95% confidence interval, 0.33-5.12). The respective values in those without chronic hypertension were 1.1% (8/749) in the aspirin group and 3.9% (30/761) in the placebo group (adjusted odds ratio, 0.27; 95% confidence interval, 0.12-0.60). In all participants with adherence of ≥90% the adjusted odds ratio in the aspirin group was 0.24 (95% confidence interval, 0.09-0.65); in the subgroup with chronic hypertension it was 2.06 (95% confidence interval, 0.40-10.71); and in those without chronic hypertension it was 0.05 (95% confidence interval, 0.01-0.41). For the complete data set the test of interaction was not significant at the 5% level (P = .055), but in those with adherence ≥90%, after adjustment for multiple comparisons, the interaction was significant at the 5% level (P = .0019).

CONCLUSION

The beneficial effect of aspirin in the prevention of preterm preeclampsia may not apply in pregnancies with chronic hypertension. There was no evidence of heterogeneity in the aspirin effect in subgroups defined according to maternal characteristics and obstetrical history.

Impaired placentation in women with chronic hypertension who develop pre-eclampsia

OBJECTIVE

To compare the degree of impaired placentation in women with and those without chronic hypertension (CH) who develop pre-eclampsia (PE) in pregnancy.

METHODS

Data were derived from prospective screening for adverse pregnancy outcomes in women with singleton pregnancy attending their first routine hospital visit at 11 + 0 to 13 + 6 weeks' gestation. This visit included recording of maternal characteristics and medical history and measurement of mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), serum placental growth factor (PlGF) and serum pregnancy-associated plasma protein-A (PAPP-A). The measured biomarkers were converted to multiples of the median (MoM) after adjustment for pregnancy characteristics. MoM values in women with CH who developed PE (n = 283) were compared to those of women without CH who developed PE (n = 2236).

RESULTS

In both groups with and without CH, measurements of MAP and UtA-PI were increased, whereas those of PlGF and PAPP-A were decreased and the deviation from normal in all biomarkers decreased with advancing gestational age at delivery with PE. There was no significant difference between women with and those without CH in the slope of the regression line of log₁₀ MoM biomarker values against gestational age at delivery with PE for any of the biomarkers. However, there was a significant difference in the intercepts and coefficients of biomarkers in the two groups; compared to those without CH, MAP MoM, PlGF MoM and PAPP-A MoM were higher and UtA-PI MoM was lower in the CH group (all P < 0.01).

CONCLUSION

In pregnancies that develop PE, the degree of impaired placentation, reflected in high UtA-PI and low PlGF and PAPP-A at 11-13 weeks' gestation, is less in women with CH than in those without CH. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.