Table 2 Summary of Kaplan-Meier survival tests & Adjusted hazard ratios for age at first birth

1395 (23.9)

21.83 (21.73–21.92)

3928 (44.7)

19.67 (19.58–19.75)

1.06 (0.98–1.14)

991.03 (p < 0.001)

2539 (63.1)

18.03 (17.93–18.14)

907 (48.8)

19.16 (18.98–19.34)

0.96 (0.88–1.05)

1772 (22.4)

21.71 (21.63–21.79)

0.70 (0.64–0.77)^***

105 (12.7)

23.38 (23.26–23.50)

0.36 (0.29–0.45)^***

3703.39 (p < 0.001)

367 (22.9)

21.94 (21.77–22.12)

1503 (25.6)

21.63 (21.53–21.72)

1.06 (0.94–1.19)

3383 (48.4)

19.30 (19.20–19.39)

0.98 (0.86–1.13)

1371.861 (p < 0.001)

1260 (57.5)

18.16 (18.00–18.32)

1429 (49.3)

19.17 (19.02–19.32)

0.89 (0.83–0.96)^**

1169 (36.0)

20.50 (20.36–20.64)

0.86 (0.79–0.94)^**

964 (28.7)

21.38 (21.26–21.51)

0.72 (0.65–0.81)^***

501 (17.1)

22.53 (22.42–22.64)

0.56 (0.49–0.64)^***

2199 (p < 0.001)

450 (5.5)

23.35 (23.29–23.41)

4873 (75.8)

18.33 (18.25–18.40)

10.60 (9.56–11.75)^***

5813.19 (p < 0.001)

768 (31.6)

21.11 (20.96–21.27)

1243 (49.1)

19.26 (19.10–19.42)

1.24 (1.12–1.37)^***

1865 (52.1)

18.81 (18.68–18.95)

1.21 (1.10–1.33)^***

325 (19.7)

22.29 (22.14–22.45)

1.02 (0.88–1.17)

675 (27.7)

21.36 (21.21–21.52)

1.45 (1.29–1.62)^***

447 (22.5)

21.96 (21.80–22.11)

1.14 (1.01–1.29)^*

1777.26 (p < 0.001)