Participant characteristics
| Study | Country | Parent mean age at start | Child age at start | Primiparous % | Intervention (n) | Control (n) |
|---|---|---|---|---|---|---|
| Feinberg and Kan39 Feinberg et al40 41 Solmeyer et al42 | USA | Mother: 28.33; Father: 29.76 | 22.9 weeks gestation | 100 | 79 | 73 |
| Hiscock et al37 Bayer et al38 | Australia | Mother: 33.1 | Child age 8 months | 54 | 329 | 404 |
| Doherty et al43 | USA | Mother: 30; Father: 31 | Second trimester | 100 | 95 | 70 |
| Vlismas et al46 | Australia | Mother: 32.62 | Child mean age 3.3 months | 100 | 24 | 24 |
| Aronen47Aronen and Kurkela48 49 Aronen and Arajärvi50 | Finland | Not reported | Child age 6 months | Not reported | 80 | 80 |
| Dickie and Gerber44 | USA | Not reported | Child mean age 8.05 months | 82 | 10 | 9 |
| Minkovitz et al45 | USA | Mother: age <20:14%, 20–29:51%, ≥30:36% | Child age 0–4 weeks | 46 | 832 | 761 |