Reference ranges and trajectories for blood pressure in pregnancy: findings from a follow-up study based on China Maternal and Newborn's Health Monitoring System

Sex-specific effects of maternal blood pressure on newborn telomere length: A prospective study

OBJECTIVE

To investigate the relationship between maternal blood pressure (BP) and neonatal cord blood telomere length (TL) during pregnancy, and to clarify the sensitive period.

METHODS

We conducted a prospective cohort study with 621 mother-newborn pairs from the Guangxi Zhuang Birth Cohort (GZBC) in China. Multiple informant models, restricted cubic spline regression (RCS) models, and quantile regression models were conducted to analyze the correlation between maternal BP and neonatal TL.

RESULTS

Maternal diastolic blood pressure (DBP) was inversely related to neonatal cord blood TL in the second trimester (P = 0.015) and the third trimester (P = 0.011). There was a male-specific relationship between maternal BP and neonatal TL. A 1 mmHg increment in maternal systolic blood pressure (SBP) and DBP during the second trimester was related with 0.42% (95% CI: -0.80%, -0.04%) and 0.61% (95% CI: -1.13%, -0.09%) shorter TL in male newborns, respectively. Per unit increase of maternal DBP during the third trimester was related with 0.54% (95% CI: -1.03%, -0.05%) shorter TL in male newborns. Pregnant women with hypertensive disease of pregnancy (HDP) had male offspring with shorter TL (P = 0.003). However, no significant relationships were found in female newborns (P = 0.570).

CONCLUSION

Maternal BP during pregnancy is inversely correlated with male neonatal TL and the second and third trimesters are sensitive windows.

Trajectory of blood pressure levels and weight gain in pregnant women: A group-based approach

BACKGROUND AND OBJECTIVES

Morbidities associated with increased blood pressure levels during pregnancy represent one of the main causes of maternal mortality. The objective was to identify patterns of systolic blood pressure (SPB) trajectory in pregnant women undergoing prenatal care at the Unified Health System, and associations with weight gain trajectory, demographic, obstetric, anthropometric data, and health related behaviors.

METHODS AND RESULTS

Cohort study with pregnant women using the public health services in Brazil. Data were collected through questionnaires and medical records. Trajectory patterns of SBP and weight gain were identified by a group-based trajectory model. For trajectory analysis, 460 women had SBP information available, totaling 2839 measurements, with an average of 6.2 measurements during pregnancy. Three SBP trajectory patterns were identified and classified as "Group 1" (48.0%), with a mean of 103 mmHg (95% CI 102.5-103.7 mmHg), "Group 2" (42.7%) with a mean of 114 mmHg (95% CI 113.7-114.9 mmHg), and "Group 3" (9.1%) with the highest mean SBP value of 130 mmHg (95% CI 128.8-131.5 mmHg). It was observed that regardless of the weight gain trajectory group, women classified in the group with the highest SBP had the highest SBP levels. The probability of being classified in Group 3 was higher among women with higher education, who started pregnancy presenting obesity, and who were using antihypertensive drugs.

CONCLUSION

The probability of belonging to groups with a greater trajectory of SBP during pregnancy was associated with obesity, education, and hypertension under treatment.

Gestational systolic blood pressure trajectories and risk of adverse maternal and perinatal outcomes in Chinese women

Background

Associations between trajectories of systolic blood pressure (SBP) during pregnancy and pregnant outcomes remain unclear and disparate.

Methods

Data of 20,353 mothers without chronic hypertension and who delivered live singletons between January, 2014 and November, 2019, was extracted from Taicang register-based cohort. Based on SBP measured during 10 to 40 weeks of gestation, SBP trajectories were explored using latent class growth mixture model, and their associations with maternal and neonatal outcomes were assessed by logistic regression analyses.

Results

Six heterogeneous SBP trajectories were identified: low delayed-increasing (7.47%), low reverse-increasing (21.88%), low-stable (19.13%), medium-stable (21.64%), medium reverse-increasing (16.47%), and high stable (13.41%) trajectories. The high-stable trajectory had SBP around 125 mmHg in the 10th gestational week, and increased slightly onwards. When compared with the low-stable trajectory, the high-stable trajectory had maximally adjusted odds ratio (95% confidence interval) of 5.28 (2.76–10.10), 1.30 (1.13–1.50), 1.53 (1.12–2.08), 1.32 (1.06–1.65) and 1.64 (1.08–2.48) for gestational hypertension (GH), early-term delivery (ETD), preterm delivery (PTD), small for gestational age and low birth weight (LBW), respectively. Besides, the medium reverse-increasing trajectory showed significantly increased risk of GH and ETD, while the medium-stable trajectory had significantly elevated risk of ETD and PTD. Notably, SBP trajectories slightly but significantly improved risk discrimination of GH, ETD and LBW, over traditional risk factors.

Conclusion

Women with different SBP trajectories were at varied risk of adverse maternal and fetal outcomes. Meanwhile, our study suggested that BP monitoring during pregnancy is necessary, especially for women with high SBP in early pregnancy or upward trajectory.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03599-7.

Neural control of blood pressure during pregnancy in humans

PURPOSE

Previous microneurographic studies found that muscle sympathetic nerve activity (MSNA) increased in normotensive pregnant women and was even greater in women with gestational hypertension and preeclampsia during the third trimester. It is possible that sympathetic activation during the latter months of normal pregnancy helps return arterial pressure to non-pregnant levels. However, when the increase in sympathetic activity is excessive, hypertension ensues. The key question that must be addressed is whether sympathetic activation develops early during pregnancy and remains high throughout gestation, or whether this sympathetic overactivity only occurs at term, providing the substrate for preeclampsia and other pregnancy-associated cardiovascular complications.

METHODS

This was a literature review of autonomic neural control during pregnancy.

RESULTS

Recent work from our laboratory and other laboratories showed that in healthy women resting MSNA increased in early pregnancy, increased further in late pregnancy, and returned to the pre-pregnancy levels shortly after delivery. We found that women who exhibited excessive sympathetic activation during the first trimester, before any clinical signs and symptoms appeared, developed gestational hypertension at term. We also found that the level of corin, an atrial natriuretic peptide-converting enzyme, was increased in the maternal circulation, especially during late pregnancy, as a homeostatic response to elevated sympathetic activity.

CONCLUSION

These findings provide important insight into the neural mechanisms underlying hypertensive disorders during pregnancy. With this knowledge, early prevention or treatment targeted to the appropriate pathophysiology may be initiated, which may reduce maternal and fetal death or morbidity, as well as cardiovascular risks in women later in life.