An Indigenous health academic says birth defects in Aboriginal communities are being missed because of inadequate medical reporting.

Janet Hammill is a speaker at the International Congress for the Prevention of Child Abuse and Neglect, which is underway in Brisbane.

Dr Hammill says many cases of foetal alcohol syndrome and foetal marijuana syndrome are not picked up until late childhood or adolescence.

She says her work with Queensland's Cherbourg Aboriginal community highlights the need for wider reporting.

"We need help for the children now, it's got to be made as good as it can," she said.

"But when you've got exposures like this over generations, then this actually equates to biological genocide.

"If we don't do something about it now, then we'll never be able to do something about it."