| Factor | Description |
|---|---|
| Birth year | Infant’s year of birth |
| Maternal age | Mother’s age at time of delivery |
| Maternal education | Mother’s highest level of education |
| Marital status | Marital status as time of delivery |
| Location of residence | Urban or rural residence |
| District health authority | Residence in Cape Breton District Health Authority or Guysborough Antigonish Strait Health Authority |
| County of residence | Residence in Antigonish, Cape Breton, Guysborough, Inverness, Richmond or Victoria County |
| Income quintile | Neighbourhood income quintile |
| Prepregnancy BMI | From self-reported weight and height at first prenatal visit; classified as underweight, normal weight, overweight or obese (Health Canada criteria (19)) |
| Parity | Primiparous or multiparous |
| Prenatal education | Whether mother received prenatal education |
| Folic acid supplementation before conception | Whether mother took folic acid supplements before conception |
| Smoking status | Nonsmoker during pregnancy, quit smoking during pregnancy or smoker at admission for delivery |
| Health condition during pregnancy | Whether mother experienced at least one of diabetes, hypertension or hyperemesis gravidarum |
| Gestational weight gain | From prepregnancy BMI and gestational weight gain; classified as suboptimal, optimal or excessive (Institute of Medicine criteria (18)) |
| Type of labour | Spontaneous, induction of labour or no labour |
| Mode of delivery | Vaginal or cesarean delivery |
| Perineal tear | Whether mother experienced third- or fourth-degree lacerations |
| Epidural analgesia | Whether mother received an epidural during labour |
| Gestational age | Preterm (< 37 weeks) or term (≥ 37 weeks) birth |
| Infant birth weight | < 2500 g or ≥ 2500 g |
| Admittance to special care nursery | Whether infant was admitted to a special care nursery |
| Infant anomaly | Presence of a major anomaly in infant (e.g., Down syndrome, congenital heart disease, cleft palate) |
| Intention to breastfeed | Whether mother intended to breastfeed; information collected at prenatal visit or admission for delivery |
| Early breast contact | Whether infant had direct contact with mother’s breast within 1 hour after birth |
Note: BMI = body mass index.