Study variables and data sources
| Variable | Source | Levels |
|---|---|---|
| Age at delivery | Antenatal maternity notes | 18–44, mean 29.5 |
| Ethnicity | Study questionnaire | Caucasian/European (91.1%), African/Caribbean (1.1%), Asian (3.9%) or other (3.9%) |
| Smoking status | Study questionnaire | Yes (18.8%) or no (81.2%) |
| Alcohol consumption | Study questionnaire | Yes (38.9%) or no (61.1%) |
| Employment | Study questionnaire | Full-time (42.3%), part-time (24.5%), unemployed (11.5%), homemaker (15%), student (2.5%), self-employed (2.2%) and other (2%) |
| Annual household income | Study questionnaire | £0–£9999 (10.4%), £10 000–£14 999 (10.4%), £15 000–£24 999 (15.9%), £25 000–£34 999 (12.9%), £35 000–£39 999 (9.2%), £40 000–£49 999 (15.1%), £50 000–£99 999 (18.4%), £100 000+ (2%) and do not know (5.7%) |
| Parity | Study questionnaire | 0–4, mean 0.8 |
| Early pregnancy BMI | Antenatal maternity notes | Overweight/obese (BMI>25 kg/m2, 46.2%), or normal (53.8%) |
| Non-specific psychological distress | Study questionnaire | 0–24, mean 4.2 (Kessler 6 scale) |
| Comorbidities (within 3 years prior to conception) | Primary care dataset | Charlson index (see online supplementary table S1) |
BMI, body mass index.