Lower placental 25-hydroxyvitamin D₃(25(OH)D₃) and higher placental CYP27B1 and 25(OH)D₃ratio in preterm birth

Neonatal mortality rates in Indonesia are still at an alarming rate, with preterm birth as one of the causes. Nutritional deficiencies such as low level of vitamin D is suspected to be the risk factors of preterm birth but still a little knowledge about it. Vitamin D metabolism includes 25-hydroxyvitamin D3 (25(OH)D3) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), as the inactive and active form, with the help of 1α-hydroxylase (CYP27B1) enzyme. Our study aims to determine the differences of 25(OH)D3, 1,25(OH)2D3 and CYP27B1 enzyme in term and preterm birth. A cross-sectional study was performed in Cipto Mangunkusumo National General Hospital, Jakarta, Indonesia, in January-June 2017. The blood sample was taken soon after delivery, to examine maternal 25(OH)D3 and 1,25(OH)2D3 in serum and tissue placenta, as well as placental CYP27B1 enzyme. Statistical analysis using SPPS version 20 was used to find significances. There were a total of sixty subjects in this study, with term-preterm birth group ratio 1:1. We found that placental 25(OH)D3 was significantly low (P = 0 .001), and CYP27B1/25(OH)D3 ratio was high in preterm birth. Also, there were significant negative correlations found in CYP27B1 level and both placental 25(OH)D3 (r 0 .481, P < 0 .001) and 1,25(OH)2D3 (r -0 .365, P = 0 .004) levels. Our study concludes that preterm birth showed lower placental 25(OH)D3 status, and higher CYP27B1/25(OH)D3 ratio compared to term pregnancy.