SRB in subgroup | BTCP | OTCP | UTCP | P |
|---|
Vaginal delivery (SRB) | 1.004 | 0.984 | 0.996 | 0.65 |
Cesarean delivery (SRB) | 1.160 | 1.119 | 1.096 | < 0.01 |
Unadjusted OR (95% CI) |
 Vaginal delivery | 1.00 | 0.98(0.95–1.01) | 0.99(0.97–1.02) | 0.37 |
 Cesarean delivery | 1.00 | 0.97(0.94–0.99) | 0.95(0.92–0.97) | < 0.01 |
Adjusted OR (95% CI) |
 Vaginal delivery | 1.00 | 0.98(0.95–1.01) | 0.98(0.95–1.01) | 0.24 |
 Cesarean delivery | 1.00 | 0.96(0.93–0.99) | 0.94(0.92–0.97) | < 0.01 |
- BTCP: Both the husband and wife of one couple were the only child of their parents, the couple were allowed to have Two Children in Policy (January 1, 2013 - May 29, 2014); OTCP: only the husband or wife of one couple was the only child of their parents, the couple were allowed to have Two Children in Policy (May 30, 2014 - December 31, 2015); UTCP: the Universal Two-Child Policy, every couple were allowed to have two children (January 1, 2016 - December 31, 2017). SRB: Sex Ratio at Birth (n (male) / n (female)); OR: Odds Ratio; 95% CI: 95% Confidence Intervals
- A chi-square test was used in the SRB at the three stages of the Two-Child Policy. BTCP acted as a control, Univariate logistic regression analysis was used to examine the strength of association between the SRB and the Two-Child Policy, and was showed in Unadjusted OR (95% CI); After adjusting the factors such as maternal age, parity, maternal education, delivery hospital, multivariate logistic regression analysis was used, and was showed in Adjusted OR (95% CI)
