Risk of preterm birth, by category of prematurity
| Timing of birth | No. (%) of pregnancies that involved use of OS or ART or both n = 2055 | Crude OR (95% CI) | Adjusted OR* (95% CI) |
|---|---|---|---|
| Term birth | 1873 (91.1) | 1.00 | 1.00 |
| Preterm birth | |||
| Late preterm (34–37 weeks’ gestation) | 134 (6.5) | 1.34 (1.12–1.59) | 1.36 (1.13–1.63) |
| Moderate preterm (32–34 weeks’ gestation) | 20 (1.0) | 1.57 (1.01–2.42) | 1.61 (1.03–2.51) |
| Very preterm (28–32 weeks’ gestation) | 16 (0.8) | 1.65 (1.01–2.72) | 1.59 (0.94–2.68) |
| Extremely preterm (< 28 weeks’ gestation) | 12 (0.6) | 2.47 (1.35–4.51) | 2.39 (1.30–4.39) |
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, infection, prior pregnancy and other medication use) and during pregnancy (smoking, obesity).