The program is proposed to include five sessions, with three antenatal sessions to be offered weekly during the 34-36 weeks gestation and two postnatal sessions weekly starting from the first week after discharge from hospital. The intervention will be delivered online.The program is designed for the intergenerational co-parenting families to undertake with parents together with grandmothers. The online courses will be delivered by an online platform in the study hospital. The first session will be pushed to participants in the intervention group within 2 days (around 34 weeks gestation) after recruitment. The second and third session will be pushed around 35 and 36 weeks gestation separately. The first postnatal session will be provided around the first to second week postpartum; and second postnatal session will be provided around the third to fourth week postpartum.

The Center for Epidemiological Studies Depression Scale (Radloff, 1977) will be used. The scale contains 20 items. The participants are asked to recall the symptoms that they experienced during the past week and respond with answers on a 4-point frequency. Each item is scored from 0 to 3, with total scores ranging from 0 to 60. A higher score indicates greater depression.

The Center for Epidemiological Studies Depression Scale (Radloff, 1977) will be used. The scale contains 20 items. The participants are asked to recall the symptoms that they experienced during the past week and respond with answers on a 4-point frequency. Each item is scored from 0 to 3, with total scores ranging from 0 to 60. A higher score indicates greater depression.

The short version of Perceived Stress Scale-4 (Cohen, 1983) will be to assess the perceived stress of co-parenting members. It consists of 4 items. Respondents rate each item with the frequency with which they experienced stress in the last month, ranging from 0 (never) to 4 (very often). The total score rangs from 0 to 16. Higher scores indicate that the respondents suffer from greater stress.

The short version of Perceived Stress Scale-4 (Cohen, 1983) will be to assess the perceived stress of co-parenting members. It consists of 4 items. Respondents rate each item with the frequency with which they experienced stress in the last month, ranging from 0 (never) to 4 (very often). The total score rangs from 0 to 16. Higher scores indicate that the respondents suffer from greater stress.

The short version of Perceived Stress Scale-4 (Cohen, 1983) will be to assess the perceived stress of co-parenting members. It consists of 4 items. Respondents rate each item with the frequency with which they experienced stress in the last month, ranging from 0 (never) to 4 (very often). The total score rangs from 0 to 16. Higher scores indicate that the respondents suffer from greater stress.

The Chinese version of The brief Co-parenting Relationship Scale (Feinberg et al., 2012; Wu, Li & Zhao, 2017) will be used to assess the co-parenting relationship between couples. The scale contains 14 items covering seven domains. Each item is rated on a 7-point Likert Scale from 0 to 6, with total scores ranging from 0 to 84. The Cronbach's alpha of Chinese version is 0.613, and the exploratory factor analysis showed Model fit was acceptable, with a reported KMO 0.748, Bartlett's χ2=686.086, P<0.01.

The Chinese version of The brief Co-parenting Relationship Scale (Feinberg et al., 2012; Wu, Li & Zhao, 2017) will be used to assess the co-parenting relationship between couples. The scale contains 14 items covering seven domains. Each item is rated on a 7-point Likert Scale from 0 to 6, with total scores ranging from 0 to 84. The Cronbach's alpha of Chinese version is 0.613, and the exploratory factor analysis showed Model fit was acceptable, with a reported KMO 0.748, Bartlett's χ2=686.086, P<0.01.

The parenting stress of parents will be measured using the Short Version of the Parenting Stress Index (Abidin & Abidin, 1990). The subscale of parental distress (PD) (12 items) and parent-child dysfunctional interaction (PCDI) (12 items) will be used in this study (Leung et al., 2005; Liu, Chen, Yeh, & Hsieh, 2012). The content validity of the Chinese version was 0.86 and the reliability was 0.91 after the removal of the DC subscale (Liu et al., 2012). Respondents are asked to rate the items using a 5-point Likert scale ranging from 1 (strongly disagree) to 5 (strongly agree). Total scores of these two subscales range from 24 to 120, with scores ranging from 12 to 60 for each subscale (Liu et al., 2012). A higher score predicts higher parenting stress.

The parenting stress of parents will be measured using the Short Version of the Parenting Stress Index (Abidin & Abidin, 1990). The subscale of parental distress (PD) (12 items) and parent-child dysfunctional interaction (PCDI) (12 items) will be used in this study (Chan et al., 2005; Liu, Chen, Yeh, & Hsieh, 2012). The content validity of the Chinese version was 0.86 and the reliability was 0.91 after the removal of the DC subscale (Liu et al., 2012). Respondents are asked to rate the items using a 5-point Likert scale ranging from 1 (strongly disagree) to 5 (strongly agree). Total scores of these two subscales range from 24 to 120, with scores ranging from 12 to 60 for each subscale (Liu et al., 2012). A higher score predicts higher parenting stress.

The Parenting Sense of Competence Scale (Gibaud-Wallston & Wandersman, 2001) will be used to assess the parenting self-efficacy of parents. This 17-item scale consists of two subscales, and has been widely used for assessments of parenting self-efficacy. Each item is rated from 1 to 6, with a total socre ranging from 17 to 102. A higher score indicates higher parenting self-efficacy. The Cronbach's alpha was 0.85 for the total scale in the Chinese version, and 0.80 and 0.77 for the subscales of Efficacy and Satisfaction, respectively. The test-retest reliability was 0.87. Good construct validity was also confirmed in the Chinese version via factor analyses, where 82% of the factors were loaded (Ngai, Chan, & Holroyd, 2007).

The Parenting Sense of Competence Scale (Gibaud-Wallston & Wandersman, 2001) will be used to assess the parenting self-efficacy of parents. This 17-item scale consists of two subscales, and has been widely used for assessments of parenting self-efficacy. Each item is rated from 1 to 6, with a total socre ranging from 17 to 102. A higher score indicates higher parenting self-efficacy. The Cronbach's alpha was 0.85 for the total scale in the Chinese version, and 0.80 and 0.77 for the subscales of Efficacy and Satisfaction, respectively. The test-retest reliability was 0.87. Good construct validity was also confirmed in the Chinese version via factor analyses, where 82% of the factors were loaded (Ngai, Chan, & Holroyd, 2007).