Preeclampsia risk is lower for women with vitamin D sufficiency in the first and third trimesters of pregnancy compared with women with vitamin D deficiency, according to findings published in Clinical Nutrition. However, vitamin D sufficiency in the first trimester alone may not be significantly associated with lower preeclampsia risk.
“Vitamin D supplementation has been suggested to be beneficial during pregnancy beyond its classical actions on calcium balance and bone metabolism,” Alexandra Benachi, MD, PhD, of the department of obstetrics and gynecology at Hôpital Antoine Béclère in Clamart, France, and colleagues wrote. “Meta-analyses and systematic literature reviews have concluded that a low maternal serum 25-hydroxyvitamin D concentration is associated with an increased risk of preeclampsia. These results on the relationship between vitamin D deficiency/insufficiency and preeclampsia suggest that vitamin D supplementation could prevent preeclampsia.”
Using a nested-control study design, Benachi and colleagues analyzed preeclampsia risk in a cohort of 3,093 pregnant women from five centers in France and one in Belgium from April 2012 to February 2015.
Among the total cohort, the researchers identified 83 women (mean age, 32.2 years) with preeclampsia, which was defined as systolic blood pressure less than 140 mm Hg or diastolic BP less than 90 mm Hg and proteinuria less than 0.3 g in 24 hours. Each of the 83 women with preeclampsia were matched with four women (mean age, 31.7 years) who did not have preeclampsia, with season at conception, skin color, BMI and maternal age the factors used for matching.
Serum 25-(OH)D concentration was measured in all participants at the first trimester and third trimester. The first trimester was considered between 11 and 15 weeks of amenorrhea, and the third was between 28 and 40 weeks of amenorrhea. A woman was considered vitamin D sufficient if she had a serum 25-(OH)D level of 30 ng/mL or more.
Although the researchers found that women with vitamin D sufficiency in the first trimester of pregnancy were at decreased risk for preeclampsia (OR = 0.57; 95% CI, 0.3-1.01), they were unable to confirm statistical significance. However, decreased risk was significant for women who had sufficiency in the first and third trimesters (OR = 0.34; 95% CI, 0.13-0.86) compared with women who had deficiency in both trimesters (P = .023). In addition, women with vitamin D sufficiency in only the third trimester had lower risk for preeclampsia (OR = 0.43; 95% CI, 0.23-0.8) compared with women who were vitamin D deficient (P = .008).
“One possible explanation for the failure of trials on vitamin D supplementation in
preeclampsia is that the current cutoffs defining vitamin D deficiency/insufficiency, which are based on osteoporosis prevention, are inappropriate for the prevention of preeclampsia,” the researchers wrote. “Another possibility is that the timing of vitamin D supplementation is not adequate. Indeed, preeclampsia is the late consequence of abnormal placentation, which occurs at the very beginning of pregnancy, and sufficient vitamin D concentrations must be present at that time. Therefore, one could suggest that the effect of vitamin D supplementation before pregnancy on the risk of preeclampsia should be assessed in clinical trials, preferably in at-risk women.” – by Phil Neuffer
Disclosures: Benachi reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.