Difference in susceptibility to teratogenic effects of alcohol in discordant twins exposed to alcohol during the second half of gestation.

A pair of discordant twins exposed to heavy maternal alcohol consumption only during the second half of pregnancy is reported. Apparently, differences in susceptibility to the dysmorphogenic influence of ethanol caused 1 twin to be more severely affected than the other. One twin had prenatal growth retardation, neonatal withdrawal symptoms, delay in both motor and cognitive function during the first year of life, slowing of background activity on electroencephalography, and cortical and central brain atrophy on computed tomography. Catch-up growth occurred during the postnatal period for the affected twin. The other twin was normal at the end of the follow-up at age 17 months. It seems that exposure to alcohol during the second half of pregnancy greatly increases the risk for brain damage but not lasting postnatal growth retardation. Minor abnormalities can also be caused during the second half of pregnancy. Genetic factors may have been important in determining the differences in fetal susceptibility to alcohol exposure.