Objective: to examine the effect of individual counselling on diet and physical activity from pregnancy to six months post partum, or from birth to six months post partum, on weight retention among Taiwanese women. Design: a randomised controlled trial assigned participants to two experimental groups [from pregnancy to six months post partum (EP) and from birth to six months post partum (EPP)] and one comparison group. Setting: a 3900-bed medical centre in northern Taiwan with around 3000 births annually. Participants: a sample of 189 women who had regular check-ups during pregnancy and gave birth at the medical centre. Interventions: the comparison group received the routine outpatient department obstetric educational programme. The EP group attended regularly scheduled clinic visits with individualised dietary and physical activity education plans from 16 gestational weeks to six months post partum, and received on brochure. The EPP group received the same educational intervention as the EP group from 24-48 hours after birth to six months post partum. Measurements: body weight, body mass index, health-promoting behaviour and psycho-social variables (self-efficacy, body image, depression and social support). Findings: average gestational weight gain was 14.02, 15.27 and 16.22. kg in the three EP, EPP and comparison groups respectively, and average weight retention at six months post partum was 2.34, 4.06 and 5.08. kg in the three groups, respectively. Key conclusions: a diet and physical activity intervention from pregnancy is effective for reducing post-pregnancy weight retention. Implications for practice: the findings of the present study should be taken into consideration when incorporating significant others and weight-loss maintenance strategies with interventions for a healthier family lifestyle.