Increased vitamin D levels before conception, but not in early pregnancy is associated with reduced risk of miscarriage (pregnancy loss). Sufficient preconception 25-hydroxyvitamin D (≥75 nmol/L) increases the chances of live birth and pregnancy. These are the results of a new study published in The Lancet Diabetes & Endocrinology.
Vitamin D deficiency during pregnancy is associated with adverse pregnancy outcomes, although the association between preconception vitamin D concentrations and livebirth is unknown. Sunni L. Mumford, the National Institutes of Health in Bethesda, Maryland, and colleagues conducted the study to assess the association between preconception vitamin D and pregnancy outcomes among 1191 women with proven fecundity.
The researchers conducted a secondary analysis of data from the placebo-controlled, block-randomized, and double-blind, EAGeR trial. Women aged 18–40 years with one to two previous pregnancy losses were recruited from June 15, 2007, to July 15, 2011, at four clinical sites in the USA and followed up for up to six menstrual cycles while attempting pregnancy and throughout pregnancy if they conceived. Serum 25-hydroxyvitamin D was measured preconception (baseline) and at 8 weeks gestation.
Outcomes of interest included clinical pregnancy, time to pregnancy, pregnancy loss, and live births. Risk ratios (RRs) and 95% CIs for live births, pregnancy, and pregnancy loss were estimated with weighted log-binomial regression.
- 555 women (47%) were classified as having sufficient concentrations (≥75nmol/L) while 636 (53%) had insufficient concentrations (<75nmol/L).
- Clinical pregnancy was more likely among women with sufficient preconception 25-hydroxyvitamin D (adjusted risk ratio [RR], 1.10) and live birth (adjusted RR, 1.15) versus women with insufficient concentrations.
- Among women who achieved pregnancy, sufficient preconception 25-hydroxyvitamin D was associated with reduced risk of pregnancy loss (preconception RR per 25nmol/L, 0.88; 95% confidence interval, 0.77 to 0.99); but this was not found at 8 weeks of gestation (RR, 0.98; 95% confidence interval, 0.95 to 1.01).
“These results provide valuable insight into the potential effects of vitamin D during the preconception period for fertile or subfertile couples attempting spontaneous conception,” concluded the authors.
For more information log on to https://doi.org/10.1016/S2213-8587(18)30153-0