Binge drinking, Having 4 drinks during a party, or having 1/2 oz, of absolute alcohol/day (1 beer, 1 glass of wine or 1 mixed drink) can cause fetal alcohol spectrum disorders. There's no known safe amt. Or time to drink when pregnant. The brain starts forming 3 weeks post-conception often before pregnancy diagnosis.It's important to stop drinking to prevent further damage. See www.Fasdcenter.Samhsa.Gov.
Toxic effect. When ethanol is broken down in the body, byproducts including acetaldehyde can have a direct toxic effect on tissue formation. There is some suggestion that some are genetically more susceptible than others. The severity of FAS correlates directly with the intensity of alcohol exposure.