Risk of preterm birth, by category of assisted reproduction
| Category | No. (%) of pregnancies | Crude OR (95% CI) | Adjusted OR* (95%CI) | |
|---|---|---|---|---|
| Term birth n = 53 947 | Preterm birth n = 3677 | |||
| Spontaneous | 52 074 (96.5) | 3495 (95.0) | 1.00 | 1.00 |
| Use of OS or ART or both | 1873 (3.5) | 182 (5.0) | 1.44 (1.23–1.69) | 1.46 (1.25–1.72) |
| Use of OS alone | 381 (0.7) | 38 (1.0) | 1.47 (1.04–2.07) | 1.47 (1.04–2.07) |
| Use of ART alone | 135 (0.2) | 15 (0.4) | 1.66 (0.96–2.87) | 1.76 (1.01–3.06) |
| Use of both OS and ART | 1357 (2.5) | 129 (3.5) | 1.41 (1.17–1.70) | 1.43 (1.19–1.73) |
Note: ART = assisted reproductive technologies, CI = confidence interval, OR = odds ratio, OS = ovarian stimulators.
↵* Adjusted for sociodemographic variables (maternal age, urban dwelling, recipient of social assistance, sex of the child) as well as maternal comorbidities measured within 12 mo before the first day of gestation (hypertension, diabetes, asthma, epilepsy, depression or anxiety, coagulopathy, other medication use, infection, prior pregnancy and other medication use) and during pregnancy (smoking, obesity).