A new report appears to contradict evidence that bottle feeding and breast feeding makes no difference in the occurrence of cot deaths when the baby sleeps in the mother's bed.
Researchers at Durham University in England have found that breast-feeding mothers instinctively adopt a safer sleeping position.
Mothers who bottle feed however, are more likely to turn their back on a sleeping infant or place it's head on a pillow level with their own.
However Professor Tom Matthews from the Irish Sudden Infant Death Association thinks there is a much stronger theory behind cot deaths.
Professor Matthews said: "There are 52 studies linking an increase in cot deaths to maternal smoking and pregnancy. We accept that link because there is a consistency in these studies.
If a small study comes out with a slightly quirky finding we all put a question mark against it until it has been looked at in several other studies. We have looked at other studies in the UK and they haven't found this result."