Elevated BP in Third Trimester of Pregnancy Linked to Increased HTN Risk

Elevated blood pressure (BP) at 28- and 34-weeks’ gestation was associated with a 2.68- and 2.45-fold, respectively, increased risk for stage I hypertension (HTN) at follow-up 5 years later, according to study results published in Clinical Endocrinology.

In this prospective, observational study, maternal BP measurements were taken at certain intervals from women participating in the ROLO study: the Randomized cOntrolled trial of a LOw glycemic index diet to prevent macrosomia (N=329). Researchers took systolic (SBP) and diastolic (DBP) blood pressure measurements during 13, 28, and 34 weeks’ gestation, day 1 postpartum, and at 5-year follow-up. Researchers identified stage I HTN as SBP 130-139 mm Hg or DBP 80-89 mm Hg and classified stage II HTN as SBP ≥140 mm Hg or DBP ≥90 mm Hg for each timepoint.

Women with elevated BP had 3-fold increased odds of having stage II HTN at follow-up (95% CI, 1.05-8.52; P =.04). At 28 and 34 weeks’ gestation, elevated BP was significantly associated with 2.68-fold and 2.45-fold increased odds, respectively, of stage I HTN at the 5-year follow-up (95% CI, 1.36-5.27; P =.004 and 95% CI, 1.22-4.95; P =.012, respectively).

Each 1-mm Hg increase in SBP and DBP at 34 weeks’ gestation was associated with 1.04 and 1.05 increased odds for stage I and II HTN, respectively, at follow-up 5 years later.

Limitations of this study include interobserver variability in reporting BP measurements. Participants’ diagnosis of HTN was self-reported, which may have resulted in some misreporting. Researchers did not include participants with mid-upper arm circumference >33 cm at the 5-year follow-up (n=57), potentially skewing the results toward participants with lower body mass index.

Although the BP measurement devices differed from gestation to follow-up, all BP measurements during pregnancy were collected using one device and all measurements at the 5-year follow-up were collected using another device; therefore, the trends and results observed are unlikely to have been affected by differences in devices used.

The researchers suggested that pregnancy is unmasking a subclinical condition that could arise later in life. For evaluation of future HTN risk, the key timepoints to assess BP are at 28 and 34 weeks’ gestation. The researchers concluded that “associations between BP at booking visit (13 weeks’ gestation) and day 1 [postpartum] (when metabolic profile is expected to return to [prepregnancy] values) with 5-year follow-up BP may indicate that those with elevated BP, HTN stage [I] or [II] at these timepoints have a degree of metabolic dysregulation prior to pregnancy.”

Reference

Brady MB, O’Brien EC, Geraghty AA, et al. Blood pressure in pregnancy – A stress test for hypertension? Five-year, prospective, follow-up of the ROLO study [published online September 26, 2019]. Clin Endocrinol. doi: 10.1111/cen.14102