Research participants
Participants were older primiparas wives and their husbands who attended maternity classes at two obstetric hospitals in A prefecture. The intervention group was consisted of couples who participated in the programme in addition to the regular maternity class, while the control group consisted of couples who participated only in the normal maternity class. The content of both normal maternity classes at the two hospitals was designed to prepare the mind and body for childbirth, the delivery process, and signs of delivery. Thus, potential bias among study participants was minimized as their degree of knowledge and preparedness regarding childbirth during pregnancy were similar.Participants were recruited through convenient sampling. The sample size was calculated using the power analysis software G *P power 3. Intervention effects were calculated at a significance level of α = 0.05, an effect size of 0.80 and a power of 0.80, the ideal sample size was 27 couples in the intervention group and the control groups, respectively.Selection criteria for participants were as follows: (1) pregnant wives age ≥35 years, (2) couples who could participate in the study during pregnancy, as well as at 1 and 3 months after childbirth, and (3) couples who could speak and understand Japanese. The following were the exclusion criteria: (1) pregnant wives and their infants with serious health problems and (2) couples with a mental illness. The programme was implemented between April 2018 and August 2019.