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: ≤24, 25-29, 30-34 and ≥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. χ 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 ≤24 years old displayed a high risk of preeclampsia. After the childbearing policy change, the maternal age ratio increased year by year. The incidences of various risk factors, delivery modes and adverse pregnancy outcomes were also changed between different years and different age groups. The differences of annual incidence showed a statistical significance besides oligohydramnios.

CONCLUSIONS

The study indicated that the changes in childbearing policy lead to the changes of age distribution proportion, which finally caused the changes of risk factors incidence. Furthermore, the advance of medical technology and society also affected the changes of pregnancy risk factors, delivery modes and the pregnancy outcomes in different years.