Inclusion Criteria:  the inclusion criteria for this study will be: (1) first time expectant parents (at least 18 years old) and should be married couples; (2) women have no pregnancy complications and around 34 weeks gestation (33-35 weeks); (3) women have regular antenatal check-ups in the study hospital and are going to deliver in the study hospital; (4) women living in Shenzhen together with husband, is cared by their mother-in-law at recruitment and will be taken care of by their mother-in-law in Shenzhen during the postpartum period; (5) Both parents and grandmothers could understand, read and speak mandarin and are willing to take part in this study; (6) Both parents and grandmothers are able to use smart phone and know how to use Wechat since the message from the online platform is pushed to Wechat in this study.  Exclusion Criteria:  Intergeneration coparenting families will be excluded if members of the family unit with reported mental health problems, such as schizophrenia, bipolar affective disorders, etc.