The influence of vitamin D on pregnancy and outcomes: Current knowledge and future perspectives.

Vitamin D deficiency increases the risk of adverse pregnancy outcomes. The high prevalence of vitamin D deficiency worldwide requires the analysis of scientific publications to make recommendations for the prevention, management and treatment of vitamin D deficiency in pregnant women. The purpose of the research was to explore the relationship between pathology and pregnancy outcomes with serum 25-hydroxycholecalciferol levels and vitamin D supplementation. A literature search was performed for systematic literature reviews with meta-analyses published between January 2018 and February 2023. 42 publications were selected for further analysis. 24 meta-analyses evaluated associations between serum 25-hydroxycholecalciferol levels on the one hand and the course and outcome of pregnancy on the other. 18 meta-analyses focused on the preventive effect of vitamin D preparations on the development of obstetric and paediatric pathology. Vitamin D deficiency was identified to increase the probability of spontaneous abortion (OR=1.6 (1.11; 2.3), preterm labour (OR=1.33 (1.15; 1.54)), especially in multiple pregnancies (OR=2.59 (1.35; 4.95)), pre-eclampsia (OR 1.58 (1.39-1.79)), anaemia of pregnancy (OR=1.61 (1.41; 1.83), postpartum depression (OR=3.67 (1.72; 7.85), autism spectrum disorders in early childhood (OR=1.54 (1.12; 2.1). High vitamin D levels reduce the risk of gestational diabetes (RR=0.87 (0.79; 0.97)), and low birth weight (RR=0.65 (0.48; 0.86)). The target level of 25-hydroxyvitamin D during pregnancy is a serum concentration of more than 30 mg/ml. Vitamin D supplementation during pregnancy at a dose of 2000 IU or higher is preventive for pre-eclampsia, insulin resistance, and the development of bronchial asthma in early childhood. Vitamin D screening is indicated for all pregnant women. Dosages of vitamin D preparations should be determined individually, considering laboratory tests and risk factors.