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Prehypertension in late pregnancy increases risk for adverse fetal outcomes
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Women who develop prehypertension in late pregnancy have a 70% increased risk for small-for-gestational-age birth and stillbirth compared with women who maintain a normal BP throughout their pregnancy, researchers reported in Hypertension.
Anna-Karin Wikstr ö m, MD, PhD, associate professor of obstetrics at Uppsala University in Sweden, and colleagues conducted a population-based cohort study of more than 150,000 women in the Stockholm-Gotland Obstetric Database. Medical records between 2008 and 2014 were examined to investigate the relationship between a mother’s BP in late pregnancy and fetal outcomes. Prehypertension was defined as systolic BP of 120 mm Hg to 129 mm Hg, diastolic BP of 80 mm Hg to 89 mm Hg, or both at 36 gestational weeks. Only single births were included.
Primary exposure was diastolic BP at 36 completed gestational weeks. The primary outcomes were giving birth to a live-born small-for-gestational-age infant or stillbirth at 37 completed gestational weeks or later.
“Working as a clinical doctor in obstetrics, I often meet women with ‘borderline high [BP],’ and I wanted to find out if they had increased risks of adverse fetal outcomes,” Wikström said in a press release.
According to the findings, prehypertension was present in 11% of the women at 36 gestational weeks. There were 2,416 small-for-gestational-age infants and 194 stillbirths. The adjusted ORs for increased risk for small-for-gestational-age birth and stillbirth were 1.69 (95% CI, 1.51-1.9) and 1.7 (95% CI, 1.16-2.49), respectively. The likelihood of having a small baby increased by 2.5% (95% CI, 1.8-3) per each mm Hg in diastolic BP at 36 gestational weeks. Women with prehypertension in late pregnancy whose diastolic BP had increased at least 15 mm Hg from early pregnancy had the highest rate (3.6%) and the highest risk (adjusted OR = 2.39; 95% CI, 2.01-2.84) for small-for-gestational-age birth. Prehypertension was more common in women with diabetes.
Wikström and colleagues wrote that women who experience a rise in diastolic BP of at least 15 mm Hg from early to late pregnancy but do not reach prehypertension levels still have an increased risk of having an underweight baby.
The researchers noted, however, that their findings only suggest an association, not a cause-and-effect relationship between BP and fetal outcomes.
“Our findings provide new insight to the relationship between maternal [BP] and fetal well-being and suggest that impaired maternal perfusion of the placenta contribute to [small for gestational age] birth and stillbirth,” Wikström and colleagues wrote. – by Tracey Romero
Disclosure: The researchers report no relevant financial disclosures.
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