Sue Jordan and colleagues from Swansea University examined data from 48,366 women.
Researchers found prostaglandins, oxytocin and ergometrine, given to induce labour and prevent postpartum haemorrhage, were associated with reductions of 6-8 per cent in breastfeeding rates.
Resultant reductions in breastfeeding rates could account for 1,000 cases of obesity a year in the UK and up to 3,000 cases of asthma in children under nine, researchers said.
Does practice need to change?The researchers said that the findings need to be confirmed in a large randomised controlled trial. 'Associations uncovered in observational research cannot be deemed causative,' they said.
In the meantime, additional resources should be put in place to support women at high risk of breastfeeding failure, but current guidelines should not be amended, the researchers argued.
'It would be unacceptable to risk an increase in morbidity and mortality from postpartum haemorrhage by using our findings to change current recommendations,' they said.
What do other experts say?
Rosie Dodds, senior public policy officer at the National Childbirth Trust, said the study was unusual in addressing how labour management can affect mothers' and babies' breastfeeding experiences.
'Many women are not provided with enough information about the medications that might be given to them during childbirth and women at low risk of bleeding may not need to take these drugs,' she said.
'It is important that women understand the risks and can give their informed consent before they go into labour,' she added. 'Women need more support to start breastfeeding soon after giving birth and this study adds weight to that.'