Research has found that a high BMI during pregnancy is likely to increase the gestation period.
Published in the International Journal of Obstetrics and Gynaecology, the study found that the risk of caesarean section, postpartum haemorrhage, maternal hypertension, gestational diabetes and foetal death are all raised when a mother to be has a high BMI.
The research was conducted at the University of Liverpool and confirmed that prolonged pregnancy was seen in 30 per cent of obese women, compared to 22.3 per cent of normal weight women.
Meanwhile, 34.4 per cent of obese women had an induction of labour, compared to 26.2 per cent of healthy weight women.
Dr Sarah Arrowsmith, from the University of Liverpool's Institute of Translational Medicine, commented: "The fact that the majority of obese women did have a vaginal delivery, with labour complications being largely comparable to normal weight women, suggests that induction of labour in obese women with prolonged pregnancy is a safe method for managing these difficult pregnancies."