SRB in subgroup | BTCP | OTCP | UTCP | P |
|---|
 Urban (SRB) | 1.053 | 1.028 | 1.045 | 0.78 |
 Rural (SRB) | 1.110 | 1.070 | 1.045 | < 0.01 |
Unadjusted OR (95% CI) |
 Urban | 1.00 | 0.97(0.95–1.00) | 0.99(0.97–1.02) | 0.08 |
 Rural | 1.00 | 0.97(0.94–0.99) | 0.94(0.92–0.97) | < 0.01 |
Adjusted OR (95% CI) |
 Urban | 1.00 | 0.97(0.94–0.99) | 0.983(0.96–1.01) | 0.13 |
 Rural | 1.00 | 0.96(0.94–0.99) | 0.934(0.91–0.96) | < 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 Two-Child Policy stages. BTCP acted as a control, univariate logistic regression 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, delivery mode, parity, education, multivariate logistic regression analysis was used, and was showed in Adjusted OR (95% CI)
