Low vitamin D during pregnancy increases risk of multiple sclerosis in offspring

Adequate vitamin intake during pregnancy is extremely important for not only the mother but also, and to an even greater degree, the health of her developing child. A new study has reported that inadequate vitamin D intake during pregnancy increases the risk of multiple sclerosis in offspring. The findings were published online on March 7 in the journal JAMA Neurology by an international team of researchers.

The study authors note that inadequate vitamin D levels have been identified as a risk factor for developing multiple sclerosis, which is a progressive, neurodegenerative disease of the central nervous system. Whether adequate maternal vitamin D levels during pregnancy are associated with risk of MS in the offspring is unclear; therefore, they conducted a study to clarify this risk.

For the study, the researchers accessed data from the Finnish Maternity Cohort conducted in May 2011. They identified 193 individuals with a diagnosis of multiple sclerosis December 31, 2009, whose mothers were in the Finnish Maternity Cohort and had an available serum sample from the pregnancy with the affected child. They matched 176 cases with 326 controls born in Finland, date of maternal serum sample collection, date of mother’s birth, and date of child’s birth.

Maternal serum vitamin D levels were measured using a chemiluminescence assay. Of the 193 offspring in the study, 163 were female. Of the 331 controls in the study, 218 were female. The majority (70%) of serum samples were collected during the first trimester (first three months) of pregnancy. The average maternal vitamin D levels were in the insufficient vitamin D range; however, higher in maternal control than in the cases (15.02 ng/mL vs. 13.86 ng/mL. The investigators found that maternal vitamin D deficiency (vitamin D levels less than 12.02 ng/mL) during early pregnancy was associated with a nearly 2-fold increased risk of multiple sclerosis in the offspring (90% increased risk) compared to women who did not have deficient vitamin D levels. There was no statistically significant association between the risk of multiple sclerosis and increasing serum vitamin D levels.

The authors concluded that insufficient maternal vitamin D during pregnancy might increase the risk of multiple sclerosis in offspring.

The American Congress of Obstetricians and Gynecologists notes that in 2010, the Food and Nutrition Board at the Institute of Medicine of the National Academies established that an adequate intake of vitamin D during pregnancy and breastfeeding was 600 international units per day, and most prenatal vitamins typically contain 400 international units of vitamin D per tablet. When vitamin D deficiency is identified during pregnancy, most experts agree that 1,000–2,000 international units per day of vitamin D is safe. Higher dose regimens used for the treatment of vitamin D deficiency have not been studied during pregnancy. In view of the foregoing, it would be prudent for a pregnant woman to take 1,000 international units of vitamin D daily.

The authors are affiliated with: Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, Massachusetts; Division of Clinical Neurosciences, Turku University Hospital and University of Turku, Finland; National Institute of Health and Welfare, Oulu, Finland; and Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts.