Table 2.

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