Maternal vitamin D status during the second trimester predicts the risk of early-onset pre-eclampsia and pre-term delivery, a new study suggests.
The study enrolled 822 pregnant women at high-risk of pre-eclampsia. Researchers measured levels of 25-hydroxy-vitamin D [25(OH)D], the main circulating form of the vitamin, in serum samples drawn between 12 and 26 weeks’ gestation.
The analysis controlled for confounders including BMI before pregnancy, the season the blood sample was taken and race.
Pre-eclampsia developed in 24 per cent of pregnancies. Early-onset pre-eclampsia, which the authors defined as <35 weeks, occurred in 7 per cent of women. Twelve per cent were vitamin D deficient (less than 30nmol/l 25(OH)D).
Compared to women with 25(OH)D levels of at least 75nmol/l, vitamin D deficient women were 2.40-fold more likely to develop early onset pre-eclampsia.
No association emerged between vitamin D status and pre-eclampsia <37 weeks.
Pre-term birth at <37 weeks and <35 weeks occurred in 27 and 11 per cent of pregnancies, respectively. Women with 25(OH)D levels <50nmol/l were 1.79-fold more likely to give birth before 35 weeks compared with those with concentrations ≥75nmol/l. Pre-term births with a medical indication (such as pre-eclampsia and hypertension) at <35 weeks’ gestation were 2.48 times commoner in women with 25(OH)D <50nmol/l versus ≥75nmol/l.
The authors remarked that the study supports the need for further research about vitamin D in high-risk pregnancies.
(BJOG DOI: 10.1111/1471-0528.14372)