Researchers at the Institute of Child Health at Bristol University investigated more than 7,900 mothers and found vegetarians were nearly five times more likely to give birth to a boy with a malformed penis - a condition known as hypospadias.
Now the team says more research is needed to support the finding, or to show it as a "rogue result". The team stresses that although only 51 boys were found with the abnormality the numbers were statistically significant.
Hypospadias is a condition where the opening of the penis is on the underside rather than the tip. It can be corrected.
The project leader, Professor Jean Golding, said: "There is no reason whatever for saying that this is anything to do with not eating meat."