Poor body image may be responsible for obese mothers stopping breastfeeding before smaller women, a study of first-time mums in Queensland has found.

Obese mothers are more likely to stop breastfeeding before smaller women and it appears poor body image is to blame, a Queensland study has found.

Half of the obese women involved in the study of first-time mothers stopped breastfeeding their newborns within six months, compared to 18 per cent of women with low body fat.

The research also found one-in-four larger pregnant women believed they would feel uncomfortable breastfeeding in front of a close female friend, compared to 10 per cent of other expectant mums.

That is despite nearly all of the women planning to exclusively breastfeed until their babies were at least six-months of age.

"The (breastfeeding) attrition rate for the larger women was so surprising," University of the Sunshine Coast researcher Dr Ruth Newby told AAP.

"We are suggesting it might be a body image issue."

When the women were surveyed while pregnant, almost half said they expected to feel embarrassed about breastfeeding in front of strangers.

But many more larger women anticipated they would feel uncomfortable if friends of both sexes were present and 25 per cent believed they would even feel uneasy breastfeeding in front of a close female friend.

Dr Newby said the study showed there was a point where issues affecting breastfeeding became insurmountable for larger women.

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She said the research, published this month, recommended further investigation into the rapid decline in breastfeeding rates among obese mothers.

"Mums want to do the best thing for their babies and we need to support them to reach their breastfeeding goals," she said.

More than 250 Queensland women responded to an antenatal and six postnatal questionnaires in the study, conducted between 2010 and 2012.