Table 3.
Results of EHA of age at first birth (n = 12912 person-years for 1537 adult females aged 15 years and over, and 19360 person-years for 1665 adult males aged 15 years and over; events = 1105 for females and 863 for males)
| Age at first birth | Female | Male | ||||
|---|---|---|---|---|---|---|
| Estimate (SE) | Hazard ratio | P | Estimate (SE) | Hazard ratio | P | |
| Mother (alive as references category) | ||||||
| Dead | −0.276 (0.119) | 0.759 | 0.02 | −0.115 (0.11) | 0.891 | 0.294 |
| Father (alive as references category) | ||||||
| Dead | −0.078 (0.089) | 0.925 | 0.383 | 0.044 (0.087) | 1.045 | 0.611 |
| Adult sister number | −0.054 (0.025) | 0.948 | 0.030 | −0.006 (0.026) | 0.994 | 0.804 |
| Adult brother number | −0.039 (0.024) | 0.962 | 0.114 | 0.029 (0.027) | 1.029 | 0.287 |
| Birth cohort (<1940 as references category) | ||||||
| 1940 | 0.722 (0.179) | 2.058 | <0.001 | 0.432 (0.215) | 1.541 | 0.804 |
| 1950 | 0.701 (0.159) | 2.015 | <0.001 | 0.4 (0.202) | 1.492 | 0.287 |
| 1960 | 0.53 (0.148) | 1.698 | <0.001 | 0.506 (0.191) | 1.658 | 0.008 |
| 1970 | 0.349 (0.146) | 1.418 | 0.017 | −0.074 (0.189) | 0.929 | 0.696 |
| 1980–1997 | −0.054 (0.152) | 0.947 | 0.721 | −0.774 (0.201) | 0.461 | <0.001 |
| Occupation (none as references category) | ||||||
| Ever had one | −0.592 (0.115) | 0.553 | <0.001 | 0.061 (0.071) | 1.063 | 0.391 |
| Constant | −28.647 (1.328) | 0 | <0.001 | −30.343 (1.462) | 0 | <0.001 |
We used complementary log–log regression for men and women separately, with first birth (one has given birth = 1, not given = 0) as dependent variable. The predictors used in the model are mother dead and father dead as time-varying variables, and adult sister number, adult brother number, birth cohort, and occupation as time-invariant variables. Significant effects are indicated in bold. SE, standard error.