Characteristics of patients (SLE) and population controls, reported as n (%) unless specified as mean (SD)
| Characteristic | SLE | Population controls | P value |
| Number of deliveries | 180 | 498 849 | |
| Maternal age (years), mean (SD) | 31.5 (5.0) | 30.4 (5.1) | 0.004 |
| <35 | 138 (76.7) | 402 064 (80.6) | |
| ≥35 | 42 (23.3) | 96 569 (19.4) | |
| Missing | – | – | |
| Parity | 0.91 | ||
| No children | 77 (42.8) | 209 978 (42.1) | |
| ≥1 child | 103 (57.2) | 288 871 (57.1) | |
| Missing | – | – | |
| Smoking in pregnancy | 12 (6.9) | 47 137 (11.2) | 0.09 |
| Missing | 6 | 79 171 | |
| BMI first trimester, mean (SD) | 23.8 (4.9) | 24.3 (4.8) | 0.30 |
| Underweight (<18.5) | 7 (8.3) | 8298 (4.1) | |
| Normal weight (18.5–24.9) | 50 (59.5) | 123 903 (61.5) | |
| Overweight (≥25) | 27 (32.1) | 69 294 (34.4) | |
| Missing | 96 | 297 354 |
BMI, body mass index; SLE, systemic lupus erythematosus.