Low Maternal Vitamin D Status during the Second Trimester of Pregnancy: A Cross-Sectional Study in Wuxi, China

Abstract

BackgroundVitamin D deficiency is common in pregnant women, but an optimal serum vitamin D level during pregnancy has not been determined and remains an area of active research. Vitamin D data from large populations of pregnant Chinese women are still limited.ObjectiveTo evaluate the vitamin D status of women in Eastern China during the second trimester of pregnancy.MethodsA hospital-based, cross-sectional, observational study. Serum 25-hydroxyvitamin D [25(OH)D] concentration was measured in samples from 5823 pregnant women in Wuxi City, China (latitude: 31.5o N), from January 2011 to June 2012.ResultsThe median serum 25(OH)D concentration was 34.0 nmol/L [2.5 nmol/L 25(OH)D = 1 ng/mL 25(OH)D]. Vitamin D deficiency [defined as 25(OH)D < 30 nmol/L according to the Institute of Medicine (National Academy of Sciences, Washington, D.C., USA)] or inadequacy [25(OH)D of 30–49.9 nmol/L] was identified in 40.7% and 38.0% of the women, respectively. Only 0.9% had a 25(OH)D level ≥ 80.0 nmol/L, which is the concentration recommended as adequate by the Endocrine Society (Washington, D.C., USA). Compared with older women, younger women were more likely to be deficient in vitamin D. There were significant differences in the 25(OH)D levels according to season. The 25(OH)D levels reached peak values in September and were correlated with (r = 0.337, P < 0.001), and fluctuated with, average monthly air temperatures.ConclusionsThere is a high prevalence of Vitamin D deficiency among pregnant Chinese women, and 25(OH)D levels varied according to season and air temperature. The results of this study also suggest that currently there is a big gap between the levels of Vitamin D detected in pregnant Chinese women and the levels recommended by the Endocrine Society.

Vitamin D Status and Its Determinants in Healthy Slovenian Pregnant Women

“…Contrary to the study results from the USA and China, we found that vitamin D levels in younger pregnant women (<30 years) were higher than in older ones (≥30 years) [35,36]. Although the results may be biased by the small size of the studied group, we may hypothesize that younger women have a longer sun exposure, and they comply more likely with prenatal care recommendations, such as folic acid supplementations, which might simultaneously contain vitamin D; the isolated vitamin D supplements during pregnancy is currently an infrequent clinical practice in Slovenia.…”

Maternal Vitamin D Status and Adverse Birth Outcomes in Children from Rural Western Kenya

“…This observation could be supported by earlier findings showing varying 25(OH)D concentrations in mothers and their children [35,38,39,40]. Our study did not collect data on risk factors influencing 25(OH)D concentrations in the population, including clothing habits, outdoor activities, and dietary habits.…”

Tracking of 25-hydroxyvitamin D status during pregnancy: the importance of vitamin D supplementation

“…Women who either did not use vitamin D supplementation or stopped supplementation after early pregnancy were younger, less-well educated, more likely to smoke, and less likely to be in their first pregnancy and had higher prepregnancy BMI. Previous cross-sectional studies have identified that younger age (19), higher BMI or weight (20)(21)(22), smoking (6,(20)(21)(22), and lower educational achievement (20) increase risk of vitamin D deficiency in pregnancy, whereas a higher parity is protective (22). Although the majority of women in this study were pregnant before the publication of the United Kingdom Department of Health guidelines that suggest that all women should receive vitamin D supplementation in pregnancy (9), similar demographic factors have also been associated with a reduced likelihood of folic acid supplementation during pregnancy (23,24).…”