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Skip Navigation Links > Competency 1: Introduction to FASD > 7. Effects of Alcohol on the Developing Embryo and Fetus

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Competency 1: Introduction to FASD

Effects of Alcohol on the Developing Embryo and Fetus

Alcohol is a teratogen, a substance that can harm a fetus. Research has established that maternal alcohol consumption is the leading preventable cause of birth defects and childhood disability in the United States.

When a pregnant woman drinks, alcohol easily crosses the placenta and enters the bloodstream of the fetus through the umbilical cord. When this happens, the blood alcohol level of the fetus can be higher than the mother’s level. The fetal blood alcohol level remains high longer because the fetus cannot break down alcohol the way an adult can. 24

Researchers do not know the amount or timing of alcohol consumption that damages the fetus. There is no known threshold amount. As few as one standard drink per week has been shown to be adversely related to child behavior at age 6 and 7. 25 Higher levels of alcohol consumption increase the risk of fetal damage. Binge drinking, four or more drinks in about two hours, can be especially harmful. 26 Maternal metabolism and alcohol's interactions with other drugs also affect the amount of damage the alcohol can cause to the fetus.

The only statement that can be made with complete accuracy is that zero exposure equals zero risk. Therefore no woman should drink at any point during her pregnancy. Women who consumed alcohol before knowing they were pregnant should stop drinking immediately. Doing so can reduce the risk of fetal harm.

Source: Moore, K.L., and Persaud, T.V.N. 1993. The Developing Human: Clinically Oriented Embryology. Philadelphia: W.B. Saunders.

FASD occurs after fertilization and is not caused by sperm. The only cause of FASD is maternal alcohol consumption during pregnancy. By definition the father cannot cause FASD.

However, scientific research has suggested that male alcohol use before conception may affect both conception and the fetus. While some studies show no discernible effects 27, others show that sons of fathers who drank alcohol, prior to conception, have memory deficits, hyperactivity, and other neurologic problems. 28,29 Some research suggests that male alcohol use can affect the motility of sperm. 30 The only way to completely avoid the risk of damaging a fetus is for both parents to be alcohol free prior to conceiving a child and for the mother to abstain from drinking alcohol throughout her pregnancy.

While men cannot cause FASD, they can help prevent FASD by helping the women in their lives remain alcohol free throughout their pregnancies. They can encourage women not to drink during pregnancy. They can also support and respect a woman’s decision not to drink. Men can also be role models for their significant others. By not drinking themselves, they are modeling the safest behavior for pregnant women. Men can help women get alcohol treatment and follow their treatment plans.

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