Vitamin D deficiency in pregnant women: Influenced by multiple risk factors and increase the risks of spontaneous abortion and small-for-gestational age

Abstract

Objective: To analyze the level of vitamin D and its influencing factors in pregnant women, and to explore the influence of vitamin D deficiency on common adverse pregnancy outcomes in pregnant women, providing evidence for prevention and intervention of vitamin D deficiency in pregnant women.

Methods: The basic data and blood samples of pregnant women in our hospital from January 2019 to June 2020 were collected, and the 25-(OH) D levels of the serum samples were detected. Then the vitamin D levels and its influencing factors were analyzed, and the relationships between vitamin D levels and common adverse pregnancy outcomes in the pregnant women as well as the incidence of small-for-gestational-age newborns were analyzed.

Results: The vitamin D deficiency rate, insufficiency rate and sufficiency rate of pregnant women were 83.28%, 15.36%, and 1.36% respectively, with vast majority of the pregnant women in a state of vitamin D deficiency. Analysis of the influencing factors on the vitamin D level of pregnant women showed "28 weeks ≤ gestational age ≤32 weeks, summer and autumn, high school education and above, weekly time outdoors ≥10 hours, supplement of vitamin D and trace elements during pregnancy" were protective factors for vitamin D sufficiency in pregnant women. Linear correlation analysis showed the vitamin D level of pregnant women was highly positively correlated with temperature, the higher the temperature, the higher the vitamin D level (r = 0.907, t = 6.818, P < .001). The level of vitamin D in pregnant women was related to the occurrence of spontaneous abortion and small-for-gestational age (SGA), with the incidence of spontaneous abortion and SGA in the "vitamin D deficiency group" higher than those of other groups (P = .018, P = .016).

Conclusions: The vitamin D level of pregnant women in this area is relatively low, which is affected by multiple factors such as gestational age, season, education level of pregnant women, weekly time outdoors, vitamin D and trace element supplement during pregnancy. Low vitamin D levels can increase the risk of spontaneous abortion and SGA in pregnant women, so relevant measures should be adopted to improve the vitamin D status of pregnant women.

Figure 1

The frequency distribution of the 25-(OH) D measurements. The concentration of 25-(OH) D of most of the cases were less than 50 nmol/L with a state of vitamin D deficiency.

Figure 2

The proportions of different vitamin D levels in the participants. Only 1.36% of the participants reached the sufficiency level of vitamin D 25-(OH) D ≥75 nmol/L.

Figure 3

The change trends of pregnant women's serum vitamin D level and temperature with month. The serum vitamin D level of pregnant women and the temperature showed a trend of synchronous change.

Figure 4

Correlation analysis of pregnant women's serum vitamin D level with temperature. The serum vitamin D level of pregnant women was highly positively correlated with temperature, with the higher the temperature, the higher the serum 25-(OH) D level (r = 0.907, t = 6.818, P < .001).