dr. beth aaronson said this time frame is critical for development. >> brains developing.ll features are forming. we all knew this was a very vulnerable period. new studies have demonstrated that this time frame is clearly when this exposure is a bad thing oar drinking alcohol during the six to 12-week mark can lead to mental impairment and puts the baby at risk for fetal infant syndrome. >> anomalies in the face, producing a ter lip, loss of the little cleft underneath the center of the nose. typically, doctors have recommended an occasional glass of wine might not ab problem during pregnancy, but i think everyone would agree that no alcohol expose sure is best. >> reporter: if you're thinking about starting a family, it's best to avoid alcohol until the baby is born. >> don't forget to log on to abc2news.com for all of your news. click on health and there yuch find health headlines as well as different health categories to help you find the information that you and your family need. >>> days are getting longer and longer. sunset will be passed. we're enjoying longer day