The changing situation about maternal age, risk factors and pregnancy outcomes after the two-child policy: a retrospective cohort study.

BACKGROUND: To evaluate the relationship between gestational age, risk factors, pregnancy outcomes, and the causes and trends of the changes in the incidence of pregnancy in different years after the two-child policy. METHODS: The study enrolled all of the childbirth women (n=7,016) from January 1st, 2015 to December 31th, 2017 in the Zhujiang Hospital. According to the age of all childbirth women, they were divided into four groups: /=35 years old. While 20-29 years old group regarded as the control group (OR =1). Pregnancy complications and outcomes data of 4 groups were collected. chi 2 test and binarylogistic regression used as the analyze method. Stratified chi-square used to compare the rates between the pregnancy risk factors, childbirth modes and pregnancy outcomes in different years, which may be affected by the age. RESULTS: Compared with the other groups, women in >/=35 years old showed the highest incidences of chronic medical complications and pregnancy induced complications, so as the abnormal neonatal birth outcomes. While women in