Endocrine Abstracts

Objective: Obesity is a major problem in pregnancy. Obesity has been associated with decreased vitamin D levels, diabetes and reproductive risks. Women were followed through pregnancy with frequent blood samples to determine any differences between lean and obese subjects. We present data on vitamin D levels through gestation in these subjects.

Methods: Normal pregnant women at 6–9 weeks GA provided blood samples every 2 weeks and body weights were recorded. We report serial serum levels of vitamin D in lean (n=8) and obese (n=6) pregnant women, and in one subject with gestational diabetes. Samples from singleton (n=35) and twin (n=31) pregnancies between 15 and 20 weeks of gestation were also analyzed in order to determine whether increased placental mass (twins) would increase vitamin D levels over singleton pregnancies. Vitamin D levels were measured by chemiluminescent immunoassay (immunodiagnostic systems).

Results: For each subject, the mean of all serial results was calculated and then the mean±S.E.M. of individual means was calculated for the lean and obese groups. Mean (±S.E.M.) vitamin D levels for the lean subjects was 28.39±1.98 ng/ml and for the obese subjects was 19.80±3.05 ng/ml. Of six lean subjects, five had a least two values or more above the sufficiency level for vitamin D (>30 ng/ml) and only one subject in the obese or gestational diabetic subjects had a value >30.0 ng/ml. Most subjects, either lean or obese, had a slight increase in serum vitamin D levels over the course of gestation. In the singleton and twin comparison at 15–20 weeks, there were no differences vitamin D levels plotted against BMI.

Discussion: Vitamin D levels are greater in lean than in obese pregnant women. Vitamin D levels are generally insufficient in the obese group and slightly increased in the lean group.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.