| Risk of first birth (until age 28.7) | Risk of first birth | ||
| Logit regression results | Proportional hazard Cox model | ||
| Birth Month | Birth Month | ||
| January | Ref. Cat. | January | Ref. Cat§. |
| February | 0.84** | February | 0.04 |
| March | 0.75* | March | 0.23 |
| April | 0.29 | April | −0.88 |
| May | 0.98** | May | 0.02 |
| June | 0.48 | June | −0.35 |
| July | 0.63 | July | −0.03 |
| August | 0.31 | August | −0.10 |
| September | 0.18 | September | −0.35 |
| October | 0.34 | October | −0.07 |
| November | 0.37 | November | −0.09 |
| December | 0.18 | December | −0.18 |
| Edu. Attainment | −0.08*** | ||