Vitamin D supplementation during pregnancy inhibits the activation of fetal membrane NF-κB pathway

Nuclear Factor-κB (NF-κB) is an important member of the basic cellular inflammatory pathway that regulates inflammation and apoptosis in fetal membranes. Vitamin D (VD) exerts its anti-inflammatory and immunomodulatory effects via the NF-κB pathway. This study was designed to investigate amniotic fluid NF-κB levels in pregnant women undergoing VD replacement therapy.

Sixty patients who received antenatal vitamin D supplementation from the 14th week of pregnancy until delivery were included in the study. Participants were selected among those whose serum vitamin D levels were compatible with insufficiency (20-30 ng/mL), according to the Endocrine Society proposal. Participants were divided into three groups with 20 patients in each group and one of the cholecalciferol or placebo treatments was given. Patients in Group 1 were given 500 IU/day of cholecalciferol, while patients in Group 2 were given 1000 IU/day of cholecalciferol. Patients in group 3 were not given cholecalciferol treatment (placebo). Patients in all groups underwent elective cesarean section. Amniotic fluid samples were collected after the fetal membranes were cut and before the fetal parts were manually removed.

The amniotic fluid NF-κB level of the control group who did not receive VD replacement was 9.33±2.02 ng/mL. The amniotic fluid NF-κB level of the 500 IU/day VD replacement group was found to be 6.12±1.23 ng/mL. Compared to the control group, NF-κB levels of pregnant women given 500 IU/day VD replacement were significantly lower (9.33±2.02 ng/mL vs. 6.12±1.23 ng/mL, p<0.03). The amniotic fluid NF-κB level of the 1000 IU/day VD replacement group was found to be 3.09±0.44 ng/mL. Compared to the control group, amniotic fluid NF-κB levels of pregnant women given 1000 IU/day VD replacement were significantly lower (9.33±2.02 ng/mL vs. 3.09±0.44 ng/mL, p<0.01). When the VD replacement groups were compared among themselves, the amniotic fluid NF-κB level decreased approximately twice as much in the 1000 IU/day replacement group compared to the 500 IU/day replacement group (3.09±0.44 ng/mL vs. 6.12±1.23 ng/mL, p<0.01). A negative correlation was found between amniotic fluid NF-κB level and VD dose (r=-0.789, p<0.04).

The present study showed for the first time that amniotic fluid NF-κB levels decreased in pregnant women who underwent VD replacement dose dependent manner.