The study analyzed the abilities of 10,534 UK seven-year-olds - some of the mothers had consumed alcohol moderately during pregnancy while some had abstained from it.
The study found little difference between the two groups and thus they advice pregnant women to ideally abstain from alcohol and even if they did consume alcohol it should be restricted to no more than two units a week.
Prof Yvonne Kelly, co-author of the study in An International Journal of Obstetrics and Gynaecology (BJOG) said: "We know heavy drinking during pregnancy has a very deleterious effect, but it is very unlikely that drinking small amounts will have an impact.
"It doesn't seem biologically plausible that small amounts of alcohol would affect development either way. The environment children grow up in is massively more important. While we have followed these children for the first seven years of their lives, further research is needed to detect whether any adverse effects from low levels of alcohol consumption in pregnancy emerge later in childhood."