There is  increasing evidence that heavy alcohol use by the male can lower the level of the male hormone testosterone, leading to low sperm counts and, occasionally, to infertility. Research shows that mothers who drink alcohol before and during pregnancy increase their risk of having children with malformations and behavioral problems. There is  increasing evidence that alcohol use by the male can lower the level of the male hormone testosterone, leading to low sperm counts and, occasionally, to infertility. Men who stop drinking during their partner’s pregnancy also help the partner avoid alcohol.

Fathers who drink heavily, even well before their children are conceived, increase their children's risk of hyperactivity, alcoholism, and/or other behavior disorders. There is some suggestion that these problems are due to direct effects of alcohol on the father's sperm or gonads.

Alcohol may cause mutations in the sperm's genetic material, or may alter the chemical composition of semen.

"Effects of paternal exposure to alcohol on offspring development," Theodore J. Cicero, Alcohol Health and Research World, Vol. 18, No. 1, Winter 1994, pp. 37-41. Address: Theodore J. Cicero, Dept. of Psychiatry, Washington University School of Medicine, St. Louis, MO.