Objective  To observe the vitamin D nutritional status and its influencing factors among women with gestational diabetes mellitus (GDM) in the last two trimesters of pregnancy.

  Methods  The high-performance liquid chromatography-tandem mass spectrometry method was adopted for the 25-OH vitamin D(25-OH VitD) detection in pregnant women with GDM visiting the outpatient nutrition clinic in Peking Union Medical College Hospital between October 2013 and July 2015. The women were divided into two groups based on whether they were taking vitamin D supplements. We surveyed vitamin D containing dietary supplements use in the vitamin D intake group, and the frequency of consumption of food high in vitamin D based on the patients' diet records.

  Results  A total of 98 pregnant women with GDM were included, with the gestational age of (29.0±3.3) weeks. The total serum 25-OH VitD was (72.03± 26.18)nmol/L. The incidence of vitamin D deficiency(< 50 nmol/L) was 20.4% (20/98). The serum 25-OH VitD level in the pregnant women was higher in the vitamin D intake group than in the non-intake group (74.35± 26.13)nmol/L vs (60.45±23.63) nmol/L, P=0.031. The vitamin D deficiency rate was 17.9% and 35.7% in the vitamin D intake group and the non-intake group, respectively. The level of serum 25-OH VitD₂ was (11.61±6.71) (6.05-24.71)nmol/L, with the detection rate of 19.4% (19/98), all in the vitamin D intake group. Serum 25-OH VitD₂ was not detected in the non-intake group. Analysis by season showed that the level of serum 25-OH VitD in pregnant women in fall/winter was significantly lower than that in spring/summer; and the vitamin D deficiency rate was significantly higher in fall/winter. The serum 25-OH VitD level in pregnant women in the vitamin D intake group was significantly higher than in the non-intake group in fall only (78.59±27.54)nmol/L vs (46.18±18.77)nmol/L, P=0.045, while no significant difference was observed in the other seasons. The vitamin D deficiency rate was 0 in both groups in summer. The dietary diary showed that the frequencies of consumption of dairy and eggs in these women were 7.5±3.8(4 cases did not take dairy) and 5.6±2.2 per week, respectively.

  Conclusions  The vitamin D deficiency rate among the pregnant women with GDM in the last two trimesters in this study is higher in fall/winte.The high detection of serum 25-OH VitD₂ may contribute to maintaining serum 25-OH VitD level among this population. The high frequency of dietary consumption of dairy products and eggs maybe help to maintain the nutritional status of vitamin D.