Parental characteristics
| Mothers n=174 | Fathers n=74 | |
| Mean age at birth (SD), years | 32 (5) | NA |
| Lone parent, n (%) | 14/172 (8) | 1/74 (1) |
| Self-reported race, n (%) | ||
| Caucasian | 108/171 (63) | 59/72 (82) |
| Black | 42/171 (25) | 7/72 (10) |
| Other | 21/171 (12) | 6/72 (8) |
| Education≥high school, n (%) | 138/168 (82) | 62/71 (87) |
| No of responses provided | 199 | 86 |
| Singleton | 139 (70%) | 60 (70%) |
| Twin or triplet | 60 (30%) | 26 (30%) |