Vitamin D Status During Pregnancy and Risk of Multiple Sclerosis in Offspring of Women in the Finnish Maternity Cohort

Abstract

<p> IMPORTANCE Vitamin D has been associated with a decreased risk of multiple sclerosis (MS)<br /> in adulthood; however, some, but not all, previous studies have suggested that in utero<br /> vitamin D exposure may be a risk factor forMS later in life.<br /> OBJECTIVE To examine whether serum 25-hydroxyvitamin D (25[OH]D) levels in early<br /> pregnancy are associated with risk of MS in offspring.<br /> DESIGN, SETTING, AND PARTICIPANTS Prospective, nested case-control study in the Finnish<br /> Maternity Cohort conducted in May 2011.We identified 193 individuals with a diagnosis of MS<br /> before December 31, 2009, whose mothers are in the Finnish Maternity Cohort and had an<br /> available serum sample from the pregnancy with the affected child.We matched 176 cases<br /> with 326 controls on region of birth in Finland, date of maternal serum sample collection,<br /> date of mother’s birth, and date of child’s birth.<br /> MAIN OUTCOMES AND MEASURES Maternal serum 25(OH)D levelswere measured using a<br /> chemiluminescence assay. The risk of MS among offspring and association with maternal<br /> 25(OH)D levels were the main outcomes. Conditional logistic regression was used and further<br /> adjusted for sex of the child, gestational age at the time of sample collection, and season of<br /> sample collection to estimate the relative risks and 95%CIs.<br /> RESULTS Of the 193 cases in the study, 163 were female. Of the 331 controls in the study,<br /> 218 were female. Seventy percent of serum samples were collected during the first trimester<br /> of pregnancy. The mean (SD) maternal vitamin D levels were in the insufficient vitamin D<br /> range, but higher in maternal control than case samples (15.02 [6.41] ng/mL vs 13.86 [5.49]<br /> ng/mL [to convert to nanomoles per liter, multiply by 2.496]). Maternal vitamin D deficiency<br /> (25[OH]D levels <12.02 ng/mL) during early pregnancy was associated with a nearly 2-fold<br /> increased risk of MS in the offspring (relative risk, 1.90; 95%CI, 1.20-3.01; P = .006)<br /> compared with women who did not have deficient 25(OH)D levels. There was no statistically<br /> significant association between the risk of MS and increasing serum 25(OH)D levels (P = .12).<br /> CONCLUSIONS AND RELEVANCE Insufficient maternal 25(OH)D during pregnancymay<br /> increase the risk of MS in offspring</p>