ABSTRACT
Objective:To investigate the pre-pregnancy vitamin D level and pregnancy outcome in patients with unexplained recurrent spontaneous abortion (URSA).Methods:A prospective study was performed in 4 534 patients with URSA from May 2017 to April 2019 at Shanghai First Maternity and Infant Health Hospital Affiliated to Tongji University. The serum Vitamin D levels was obtained before pregnancy. Pregnancy complications and newborns outcomes were recorded after pregnancy.Results:The serum vitamin D level of patients with URSA before pregnancy was (42.22±16.27)nmol/L, and the proportions of vitamin D deficiency, insufficiency and sufficiency were 72.3%, 24.0 %, and 3.7%, respectively. The Vitamin D level was positively correlated with age ( P<0.05); The age of vitamin D<50 nmol/L group was lower than that of vitamin D≥50 nmol/L group ( P<0.05); patients with vitamin D<50 nmol/L had higher proportion of spontaneous abortions ≥3 times than those with the vitamin D≥50 nmol/L ( P<0.05); The level of vitamin D was negatively correlated with the ratio of CD3 + CD4 + T cells in peripheral blood ( P<0.05); In multivariate logistic regression analysis, the final model adjusted for age, abortion frequency and season. The risk of pregnancy failure was increased in vitamin D <50 nmol/L group [30.6%(76/248) vs 17.9%(12/67), χ 2=3.67, P=0.02], OR=2.02(95% CI: 1.02-3.9); In the group of vitamin D<50 nmol/L before pregnancy, the risk of newborns entering NICU was increased, OR=3.16(95% CI: 1.15-8.65). Conclusions:Vitamin D deficiency is prevalent in URSA patients before pregnancy, which correlates with the times of previous spontaneous abortions and recurrent pregnancy failure. Vitamin D deficiency before pregnancy is one of the high-risk factors for URSA.