Vitamin D deficiency in adolescent pregnancy and obstetric outcomes

The aim of this study was to evaluate the rates of vitamin D deficiency in adolescent pregnants and its influence on the obstetric outcomes.

A total of 300 singleton pregnant women aged between 14 and 20 years, were divided into three groups according to their gestational weeks (100 pregnant adolescents from each trimester). Randomly selected 300 singleton pregnant women older than 20 years of age with the similar gestational ages were designed as the control group at the same time period. We divided serum 25(OH)D levels into three categories deficiency, inadequacy and adequate levels according to the Endocrine Society guidelines. Serum 25(OH)D levels were also evaluated according to age, seasons and gestational periods. Adverse obstetric outcomes were recorded.

Overall, 86% of the subjects were found to have deficient 25(OH)D levels (<20 ng/ml). The levels indicated an inadequate state in 72 subjects (12%) and only 12 (2%) women had adequate 25 (OH) D levels. Among adult pregnant women the rates of deficient, inadequate and adequate levels were 88.3%, 11%, and 0.7% respectively. Among adolescent pregnant women these rates were 83.7%, 13%, and 3.3% respectively. The lowest 25(OH)D levels occurred during the winter while the highest levels were detected during the summer in both groups. Calcidiol, 25(OH)D, was a significant predictor for preterm delivery (AUC = 0,909; p < 0,001) and also for SGA (AUC = 0,915; p < 0,001). Maternal age was another significant predictor for SGA (AUC = 0,787; p < 0,001) and preterm delivery (AUC = 0,785; p < 0,001).

We found a high incidence of 25(OH)D deficiency in Turkish pregnant women. Adolescent age and low 25(OH)D levels are significant risk factors for PTD and SGA. Effective prophylaxis programs for vitamin D deficieny and/or fortification of foods with vitamin D are essential in pregnant women especially in the winter season.