Association between conception by assisted reproductive technologies and childhood asthma at 7 years
| Study population | Conceived by assisted reproductive technologies | N | N cases (%) | Unadjusted RR (95% CI) | Adjusted* RR (95% CI) |
| Register-based cohort | No | 466 034 | 19 760 (4.2) | 1 | 1 |
| Yes (total) | 8368 | 429 (5.1) | 1.21 (1.10 to 1.33) | 1.20 (1.09 to 1.32) | |
| Yes (IVF) | 7339 | 377 (5.1) | 1.21 (1.10 to 1.34) | 1.20 (1.08 to 1.33) | |
| Yes (ICSI) | 483 | 25 (5.2) | 1.22 (0.83 to 1.79) | 1.21 (0.83 to 1.76) | |
| Yes (other/unspecified) | 546 | 27 (5.0) | 1.17 (0.81 to 1.69) | 1.15 (0.79 to 1.65) | |
| MoBa | No | 74 406 | 3144 (4.2) | 1 | 1 |
| Yes | 1391 | 85 (6.1) | 1.45 (1.17 to 1.78) | 1.42 (1.14 to 1.76) |
*The analysis of the register-based cohort was adjusted for maternal age, parity and maternal current asthma. The analysis of MoBa was adjusted for maternal age, parity, education, smoking during pregnancy, prepregnancy BMI and maternal current asthma.
BMI, body mass index; ICSI, intracytoplasmic sperm injection; IVF, in vitro fertilisation; MoBa, Norwegian Mother and Child Cohort Study; RR, relative risk.