Vaginal Administration of Progesterone in Twin Gestation: Influence on Bone Turnover and Oxidative Stress

Twin pregnancies, with higher incidences of preterm birth, are becoming more prevalent. Progesterone has shown effectiveness in the prevention of preterm labour, though other factors related to pregnancy and neonatal health may be affected by this hormone and have not been previously addressed. This study aims to evaluate the impact of progesterone administration on oxidative stress and bone turnover during twin gestation and investigate associations with some maternal/neonatal variables of interest. Women pregnant with twins were recruited in the "Virgen de la Arrixaca" University Hospital and randomly assigned to two groups: control (n = 49) and progesterone (n = 50). A total of 600 mg/day of progesterone was vaginally administered from 11 to 14 to 34 weeks of gestation. Blood samples were taken in the first (T1) and third trimester (T3), analyzing biomarkers related to oxidative stress and bone turnover. Most bone turnover and oxidative markers experiment with significant changes during gestation. Progesterone administration significantly increased (<i>p</i> < 0.05) the levels of osteocalcin in T3 and decreased (<i>p</i> < 0.05) the levels of sclerostin. Regarding oxidative stress, the progesterone group, unlike the control group, showed no significant increase in oxidative stress between T1 and T3. In conclusion, results show that progesterone administration could increase maternal bone formation and modulate oxidative stress.