Association between Preterm Premature Rupture of Membranes and Vitamin D Levels in Maternal Plasma and Umbilical Cord Blood of Newborns: A Prospective Study

Background: Preterm premature rupture of membranes (PPROM) is a major cause of preterm birth. There are few reports on vitamin D deficiency associated with PPROM. We aimed to investigate the association between PPROM and vitamin D levels in maternal plasma and the umbilical cord blood of newborns. Methods: This prospective study included 355 pregnant women who delivered live infants between March 2017 and December 2018 at a medical center. Vitamin D levels were measured in the maternal plasma at the first, second, third trimesters of pregnancy and just before delivery, and in the umbilical cord blood of newborns at birth. In addition, we evaluated the pregnancy and neonatal outcomes according to vitamin D status. Results: The rate of PPROM in the vitamin D deficiency group (25(OH)D <20 ng/mL) was higher than in the non-deficiency group (25(OH)D >= 20 ng/mL) (p = 0.003). Vitamin D levels were significantly lower in the PPROM group than non-PPROM group in maternal plasma [at the first (p = 0.020) and second trimesters (p = 0.029), just before delivery (p = 0.015)], and in the cord blood of newborns (p = 0.006). Multiple logistic regression analysis showed that the odds ratio of PPROM by the increase of 1ng/mL of vitamin D levels in the cord blood of newborns was 0.907 (95% confidence interval 0.836-0.983) after adjustment for other confounders (age, gravidity, parity, and body mass index). Conclusions: Vitamin D deficiency has a significant association with PPROM. Our study would aid in understanding the mechanism of prevention of PPROM associated with vitamin D deficiency as well as reduction in preterm births.