This study aims to determine the effect of midwife’s supportive care during labour on onset of lactogenesisII and exclusive breastfeeding. In a randomized clinical trial study, 80 primigravida women in Omolbanin Hospital in Mashhad will be recruited. The inclusion criteria for subjects are:gestational age 38-42 weeks, single foetus and live with cephalic presentation, cervical dilation 3-4 cm, no medical and obstetric complications and no evidence of fetal distress. Subjects will be allocated randomly into supportive care and usual care groups. Women with medical complications and congenital malformations in infant will be excluded. Experimental group will receive supportive care including physical, educational and emotional support during active phase of labour and also the first hours after delivery by the researcher. Control group will receive usual labour and delivery care by staff midwives. Labour progress and breastfeeding status will be monitored and recorded by the researcher in both groups. In both groups appearance of clinical symptoms of lactogenesisII (mother reports milk leaking) will be determined through daily phone contacts during postpartum period. In addition mothers will be asked to fill a daily checklist about infants feeding from birth until the sixth weeks following delivery. The onset of lactogenesis II and frequency of exclusive breastfeeding at the end of four and six weeks will be compared in the two groups.