Alcohol: Fertility and pregnancy

A study of 430 couples in Denmark found fertility to decline among women as their alcohol consumption increased, but no effect was observed on male fertility. In contrast, a study of farm couples in Canada found no difference in fertility between women who did or did not drink alcohol.

Still another study, in the Netherlands, found male alcohol consumers to have higher fertility as consumption increased, with no difference in fertility rate between women who drank different amounts. Such findings of sometimes yes, sometimes no, are a classic sign of an “invalid variable,” which in this case would mean that no difference in fertility can be attributed to alcohol (although more studies would be needed to reach a firm conclusion, and some authorities say the trend of research indicates that alcohol does reduce female fertility).

A study found that premature infants were more likely among pregnant teenagers who drank alcohol than among those who did not. That effect was not seen among older pregnant women who drank. Other research has noted lower birthweights among children delivered by pregnant alcohol consumers. A human experiment documented fetal response to two glasses of wine drunk by women whose pregnancies were close to time of delivery: In that experiment fetal respiration and sleep were disturbed—which did not surprise researchers because heavy consumers of alcohol frequently give birth to infants having sleep difficulties. Such newborns may also have tremors and poor reflexes and cry more than normal. Children can be born dependent on the drug.

Alcohol is a well-known cause of birth defects. In mice the substance is known to cause a facial deformity called holoprosencephaly, and a human case report suggests that heavy dosage can do the same in humans. Less dramatic facial characteristics are common after substantial prenatal exposure to alcohol. Other human birth defects attributed to alcohol include kidney, heart, and brain trouble. More subtle damage has been measured as a slight decline in IQ among schoolchildren of mothers who took two or more drinks a day during pregnancy. Male exposure to some drugs can produce birth defects, and researchers have found problems in behavior and thinking skills among children of alcoholic fathers as well as among offspring of pregnant alcoholics. Fetal alcohol syndrome (FAS) is a collection of afflictions observed in children typically born to women who had six or more drinks a day while pregnant. The syndrome may include low birthweight, defective vision, delayed development, specific facial characteristics, trouble with muscles and joints, heart abnormality, and mental retardation. Problems can be long-lasting and even permanent. Prenatal exposure to alcohol can delay motor skill development in children, cause difficulties in maintaining balance, and limit growth in height.

Such children may be more impulsive and aggressive. A study of adolescents compared two groups, one born with FAS and another whose mothers drank little or no alcohol during pregnancy. The FAS group showed impairment in some types of memory, attention, thinking, and learning—findings supported by other research as well. Some researchers believe that fetal exposure to alcohol has more to do with teenage drinking than family environment does. Comparing adults with heavy prenatal alcohol exposure to those without such exposure, a small study measured significant psychiatric differences, particularly with the alcohol subjects being more depressed and fearful.

Fetal damage from maternal alcohol use is unquestionable, but the amount of use necessary to cause damage is less certain and can be affected by a woman’s general physical condition and lifestyle (including nutrition and other drug usage). Occasional binge drinking and routine heavy drinking are certainly hazardous to fetal development, but for many years pregnant women have used alcohol in moderation without apparent effect on offspring. Nonetheless, in general, women are now advised to avoid any alcohol consumption during pregnancy.

Experimenters note that alcohol consumption reduces mothers’ milk production but does not affect energy provided by the milk. Alcohol levels in milk are similar to a mother’s blood levels. A nursing infant may be sickened by milk from a mother who abuses alcohol—an infant has not yet developed the proper body chemistry to break down alcohol, so a dose lasts longer in an infant than in an older child or adult.

Reference: The Encyclopedia of addictive drugs – Richard Lawrence Miller ISBN: 0–313–31807–7