Early Pregnancy Systolic Blood Pressure Patterns Predict Early- and Later-Onset Preeclampsia and Gestational Hypertension Among Ostensibly Low-to-Moderate Risk Groups

Early pregnancy maternal blood pressure and risk of preeclampsia: Does the association differ by parity? Evidence from 14,086 women across 7 countries

OBJECTIVE

To determine if the relationship between blood pressure (BP) before 16 weeks' gestation and subsequent onset of preeclampsia differs by parity, and by history of hypertensive disorders of pregnancy (HDP) in parous women.

STUDY DESIGN

Data from two studies were pooled. First, routinely collected clinical data from three metropolitan hospitals in Sydney, Australia (2017-2020), where BP was measured as part of routine clinical care using validated mercury-free sphygmomanometers. Second, prospectively collected research data from the INTERBIO-21st Study, conducted in six countries, investigating the epidemiology of fetal growth restriction and preterm birth, where BP was measured by dedicated research staff using an automated machine validated for use in pregnancy.

MAIN OUTCOME

Adjusted odds ratios (aOR) (95% confidence interval (CI)) for the association of systolic BP (SBP), diastolic BP (DBP) and mean arterial pressure (MAP) with preeclampsia were obtained from logistic regression models. Models were adjusted for age, smoking, body mass index, previous hypertension, previous diabetes, and previous preeclampsia. Interactions for parity, and history of HDP in parous women were included.

RESULTS

There were 14,086 pregnancies (Sydney = 11008, INTERBIO-21st = 3078) in the pooled analyses, 6914 (49 %) were parous, of which 414 (6.0 %) had a history of HDP. Nulliparous women had a higher risk of preeclampsia (2.6 %) compared with parous women (1.5 %): [aOR (95 %CI) 3.61 (2.67, 4.94)], as did parous women with a history of HDP (15.0 %) compared with no history (0.7 %) [12.70 (8.02, 20.16)]. MAP before 16 weeks' gestation (mean [SD] 78.8[8.6] mmHg) was more strongly associated than SBP or DBP with development of preeclampsia in parous women [2.22 (1.81, 2.74)] per SD higher MAP] compared with nulliparous women [1.58 (1.34, 1.87)] (p for interaction 0.013). There were no significant differences on the effect of blood pressure on preeclampsia in parous women by history of HDP (p for interaction 0.5465).

CONCLUSION

The risk of preeclampsia differs according to parity and history of HDP in a previous pregnancy. Blood pressure in early pregnancy predicts preeclampsia in all groups, although more strongly associated in parous than nulliparous women, but no different in parous women by history of HDP.

The impact of vitamin D changes during pregnancy on the development of maternal adverse events: a random forest analysis

BACKGROUND

Maternal vitamin D deficiency during pregnancy has been associated with various maternal adverse events (MAE). However, the evidence regarding the effect of vitamin D supplementation on these outcomes is still inconclusive.

METHODS

This secondary analysis utilized a case-control design. 403 samples with MAE and 403 samples without any outcomes were selected from the Khuzestan Vitamin D Deficiency Screening Program in Pregnancy study. Random forest (RF) analysis was used to evaluate the effect of maternal vitamin D changes during pregnancy on MAE.

RESULTS

The results showed that women who remained deficient (35.2%) or who worsened from sufficient to deficient (30.0%) had more MAE than women who improved (16.4%) or stayed sufficient (11.8%). The RF model had an AUC of 0.74, sensitivity of 72.6%, and specificity of 69%, which indicate a moderate to high performance for predicting MAE. The ranked variables revealed that systolic blood pressure is the most important variable for MAE, followed by diastolic blood pressure and vitamin D changes during pregnancy.

CONCLUSION

This study provides evidence that maternal vitamin D changes during pregnancy have a significant impact on MAE. Our findings suggest that monitoring and treatment of vitamin D deficiency during pregnancy may be a potential preventive strategy for reducing the risk of MAE. The presented RF model had a moderate to high performance for predicting MAE.