Objective To analyze the risk factors associated with and the outcome of macrosomic babies (birth weight more than 4500 g).

Methods Retrospective review of records of 44 macrosomic babies delivered between January and September 2009 at West Middlesex University Hospital, Isleworth.

Results 1.47% of the babies were macrosomic. Mean birth weight was 4676 g (range from 4500 to 5220 g). Increased body mass index (BMI) was not associated with macrosomia (84% of babies were born to mothers with BMI less than 30). None of the mothers had either gestational or established diabetes. None of the babies were preterm. 91% of macrosomic babies were delivered after 40 completed weeks and 30% of babies were after 42 completed weeks.

Out of 44 mothers, 61% went in to spontaneous labour, 29% were induced and 9% had elective caesarean section. Out of 40 mothers who went in to labour, 65% delivered spontaneous vaginally, 7.5% had instrumental delivery and 27.5% had emergency caesarean section. Higher birth weight was associated with higher caesarean section rate (60% in birth weight more than 5000 g). Shoulder dystocia occurred in 11.36%. Postpartum haemorrhage occurred in 36.36% of the deliveries and a significant proportion was due to trauma (seven out of 16).

Conclusion Effective diabetic management probably could have contributed to no macrosomic babies in diabetic mothers. Commonest maternal complications were emergency caesarean section and haemorrhage. Commonest fetal complication was shoulder dystocia. Over all out come for the mother and baby were good and vaginal delivery should be the option for most macrosomic babies.