High prevalence of maternal vitamin D deficiency in preterm births in northeast China, Shenyang.

Introduction: Maternal vitamin D deficiency has been associated with a number of fetal and neonatal health problems. Preterm birth is one of the most detrimental, and the role of maternal vitamin D deficiency in preterm births has not been universally acknowledged. There had been limited epidemiological studies of vitamin D deficiency on the Chinese population.
Subjects and Methods: 1103 women delivered in Shengjing Hospital, China Medical University from January 1(st), 2012 to January 1(st), 2013. Finally, 821 mother-newborn pairs which contained 143 mother-newborn pairs who were preterm delivery were recruited for analysis.
Results: There was significant difference between spring and summer (P<0.0001) as well as spring and autumn (P<0.01). Compared to those in summer and autumn, the 25 (OH) D level was significantly lower in winter (summer vs winter P<0.0001, autumn vs winter P<0.0001). Maternal vitamin D level showed obvious variation with months and seasons, with higher level in summer months and lower level in winter months. There were significant difference between the vitamin D level of the very preterm group and the mildly preterm groups (P<0.01), as well as the very preterm group and the in-term groups (P<0.001). Prevalence of Vitamin D deficiency occurred in 63.04% of pregnant women in very preterm group, compared with 36.61% in in-term group.
Conclusion: Vitamin D nutritional status of pregnant women and their newborns in Shenyang were relatively good compared to cities in similar latitudes. Vitamin D deficiency was most severe in late spring and least in summer. Severe preterm births before 31 weeks of gestation was associated with maternal vitamin D deficiency.