The end of the first trimester appears to be the period when alcohol can wreak the most havoc on fetal development.
Researchers say it can cause physical deformities, as well as behavioral and cognitive symptoms.
Study authors also stressed that their research shows there is no safe amount of drinking during pregnancy.
They say the amount of drinking that produced these features in infants varied from woman to woman.
The study is on line in the journal Alcoholism: Clinical and Experimental Research.