Table 2 Changes in birth characteristics during China’s two-child policy
Monthly percentage % (mean (standard deviation)) | The partial two-child policy period | The universal two-child policy period | ||||||
|---|---|---|---|---|---|---|---|---|
one-child policy period | partial two-child policy period | universal two-child policy period | Level change β2 (95% CI, P-value) | Trend change β3 (95% CI, P-value) | Level change β4 (95% CI, P-value) | Trend change β5 (95% CI, P-value) | ||
Maternal characteristics | mother age ≥ 35 | 7.39 (0.72) | 10.59 (0.72) | 13.65 (1.42) | 3.42 (3.04 to 3.81, < 0.001) | −0.01 (− 0.04 to 0.03, 0.861) | 0.97 (0.49 to 1.46, 0.045) | 0.24 (0.19 to 0.28, < 0.001) |
Nulliparous births | 2.51 (0.72) | 5.29 (0.51) | 6.46 (1.06) | 1.64 (1.38 to 1.9, < 0.001) | −0.01 (− 0.03 to 0.01, 0.513) | −0.25 (− 0.58 to 0.07, 0.438) | 0.13 (0.1 to 0.16, < 0.001) | |
Multiparous births | 18.27 (2.13) | 19.89 (1.29) | 24.03 (1.95) | 4.5 (3.75 to 5.24, < 0.001) | 0.04 (−0.02 to 0.1, 0.513) | 1.61 (0.68 to 2.55, 0.087) | 0.31 (0.23 to 0.4, < 0.001) | |
Birth outcomes | Caesarean delivery | 54.02 (3.58) | 47.86 (1.62) | 47.73 (1.45) | −3.84 (−5.44 to −2.25, 0.018) | −0.03 (− 0.16 to 0.09, 0.786) | −0.81 (− 2.81 to 1.2, 0.688) | 0.21 (0.03 to 0.4, 0.254) |
Nulliparous births | 57.19 (5.19) | 44.51 (2.12) | 43.73 (1.58) | −5.77 (−7.64 to −3.9, 0.003) | −0.01 (− 0.16 to 0.14, 0.97) | −0.97 (− 3.32 to 1.39, 0.683) | 0.29 (0.07 to 0.51, 0.186) | |
Multiparous births | 46.88 (4.68) | 53.82 (1.8) | 53.52 (1.7) | −0.55 (−1.71 to 0.61, 0.634) | − 0.11 (− 0.2 to − 0.01, 0.253) | −1.65 (− 3.11 to − 0.19, 0.26) | 0.02 (− 0.11 to 0.16, 0.861) | |
Sex ratio | 114.32 (4.33) | 110.44 (3.22) | 109.86 (3.81) | −0.86 (− 1.31 to − 0.4, 0.062) | 0.06 (0.02 to 0.1, 0.11) | −0.06 (− 0.64 to 0.51, 0.911) | −0.1 (− 0.15 to − 0.05, 0.065) | |
Nulliparous births | 107.61 (4.51) | 106.54 (3.75) | 106.71 (4.45) | −3.45 (− 5.75 to − 1.15, 0.136) | 0.27 (0.08 to 0.45, 0.149) | 0.29 (− 2.61 to 3.18, 0.922) | − 0.52 (− 0.79 to − 0.25, 0.056) | |
Multiparous births | 131.51 (10.48) | 117.78 (6.47) | 114.61 (5.79) | −7.63 (− 12.26 to − 3.01, 0.102) | 0.28 (− 0.09 to 0.65, 0.453) | −2.26 (− 8.08 to 3.56, 0.699) | − 0.3 (− 0.85 to 0.24, 0.582) | |
Gestation < 37 weeks | 5.22 (0.97) | 7.77 (0.66) | 7.84 (0.73) | 0.69 (0.35 to 1.02, 0.041) | 0.03 (0 to 0.06, 0.241) | −1.15 (− 1.56 to − 0.73, 0.007) | 0.01 (− 0.03 to 0.05, 0.845) | |
Nulliparous births | 4.55 (0.85) | 6.67 (0.73) | 6.85 (0.71) | 0.41 (0.08 to 0.74, 0.216) | 0.05 (0.02 to 0.08, 0.058) | −1.17 (− 1.58 to − 0.75, 0.006) | 0 (− 0.04 to 0.04, 0.918) | |
Multiparous births | 6.72 (1.49) | 9.71 (0.93) | 9.27 (0.97) | 0.72 (0.19 to 1.25, 0.174) | 0 (− 0.04 to 0.04, 0.962) | −1.38 (−2.05 to − 0.72, 0.04) | 0.02 (− 0.05 to 0.08, 0.804) | |
Birth weight < 2500 g | 3.67 (0.56) | 5.3 (0.54) | 5.36 (0.43) | 0.53 (0.3 to 0.77, 0.024) | 0.04 (0.02 to 0.06, 0.036) | −0.83 (−1.12 to − 0.53, 0.006) | −0.01 (− 0.04 to 0.02, 0.706) | |
Nulliparous births | 3.22 (0.52) | 4.72 (0.68) | 4.86 (0.35) | 0.41 (0.17 to 0.65, 0.092) | 0.05 (0.03 to 0.07, 0.008) | −0.67 (− 0.97 to − 0.36, 0.031) | −0.04 (− 0.07 to − 0.01, 0.182) | |
Multiparous births | 4.68 (0.96) | 6.34 (0.62) | 6.09 (0.73) | 0.48 (0.07 to 0.9, 0.249) | 0.02 (−0.01 to 0.05, 0.572) | −1.2 (− 1.72 to − 0.68, 0.023) | 0.03 (− 0.02 to 0.07, 0.605) | |
Birth defect | 0.98 (0.19) | 1.17 (0.3) | 0.82 (0.15) | 0.28 (0.18 to 0.39, 0.009) | −0.01 (− 0.02 to 0, 0.386) | −0.17 (− 0.3 to − 0.03, 0.216) | 0 (−0.02 to 0.01, 0.755) | |
Nulliparous births | 0.96 (0.23) | 1.12 (0.31) | 0.76 (0.18) | 0.34 (0.22 to 0.47, 0.007) | −0.01 (− 0.02 to 0, 0.312) | −0.17 (− 0.33 to − 0.02, 0.271) | 0 (−0.01 to 0.02, 0.874) | |
Multiparous births | 1.02 (0.34) | 1.24 (0.41) | 0.9 (0.22) | 0.14 (−0.03 to 0.32, 0.42) | 0 (−0.02 to 0.01, 0.893) | − 0.18 (− 0.4 to 0.04, 0.426) | −0.02 (− 0.04 to 0, 0.407) | |