Changes of second-time mothers and their infants under the universal two-child policy in Changsha, China

China announced the implementation of the universal two-child policy in Oct, 2015; every couple was allowed to have two children. However, its influences on maternal well-being and infants’ outcomes are still to be discovered. To detect influences of the universal two-child policy. To provide information for maternal health care under the new policy. This study enrolled 859 and 1230 women who delivered their second child (hereafter second-time mothers) before and after the policy's implementation, respectively, and the data included maternal demographic characteristics, gestational complications, delivery mode and infants’ outcomes. After the policy's implementation, the proportion of second-time mothers with advanced age increased significantly. The advanced gestational age is well acknowledged to correlate with higher risk during the pregnancy, both for pregnant women and their babies. However, in our study, the incidence of hypertensive disorders in pregnancy, placenta previa and postpartum haemorrhage decreased significantly after the introduction of the policy and no differences were noted in other gestational complications. Moreover, the hospitalization time was shortened, and caesarean delivery was chosen less frequently. As for the infants, foetal distress exhibited an alleviation and the incidence of premature labour and low birth weight decreased as well. Even though the age of second-time mothers increased after the introduction of the universal two-child policy, their general gestational health condition improved and their infants also exhibited a better outcome, which might be attributed to the improvement of China's maternal medical care system.