Alcohol During Pregnancy May Harm Sons' Sperm
Here is another reason why women should not drink alcohol during pregnancy. Scientists in Denmark discovered that the sperm concentrations of sons born to women who drank 4.5 or more drinks weekly during pregnancy were 32 percent lower when compared with men who were not exposed to alcohol while in the womb.
The results of this research are being presented at the 26th annual meeting of the European Society of Human Reproduction and Embryology in Rome. During a news briefing, Dr. Cecilia Ramlau-Hansen, senior researcher at the Department of Occupational Medicine, Aarhus University Hospital in Denmark and clinical professor at the Department of Epidemiology, Institute of Public Health, University of Aarhus, noted that “because this is an observational study we cannot say for certain that the alcohol causes the lower sperm concentrations.”
She further explained that it is possible that drinking alcohol during pregnancy may have a negative impact on the fetal tissue in the testes that produce semen, and thus in this way affect semen quality in later life. However, this study “is the first of its kind,” she noted, “and more research within this area is needed before any causal link can be established or safe drinking limits proposed.”
This unique study included 347 sons of 11,980 women who had been part of the Danish “Healthy Habits for Two” study that was conducted between 1984 and 1987. At that time, all the mothers answered a questionnaire on lifestyles and health around their 36th week of pregnancy.
The sons were followed up between 2005 and 2006, when they were between 18 and 21 years old. At that time, they provided semen and blood samples for analysis. The sons were then divided into four groups, based on their exposure to alcohol during their mothers’ pregnancy: less than one drink a week, 1 to 1.5 drinks per week, 2 to 4 drinks per week, and 4.5 or more drinks per week. A “drink” was defined as 12 grams of alcohol, which is the equivalent to 120 ml of wine, 40 ml of spirits, or 330 ml of beer.
The sons of women who drank 4.5 or more alcoholic drinks per week had an average sperm concentration of 25 million per milliliter, while the sons who had the least exposure to alcohol had sperm concentrations of 40 million/ml. After the scientists adjusted for other factors, the sons who were most exposed to alcohol had a sperm concentration that was approximately 32 percent lower than those in the least exposed group.
The good news is that the men in the most exposed group had sperm concentrations that are within the World Health Organization’s definition of “normal,” which is 20 million/ml or higher. Dr. Ramlau-Hansen pointed out that men in the most exposed group were near the “lower end of the WHO’s normal range for fertility,” and that the chances of conception improves with sperm concentrations up to 40 million/ml. “So it is possible that the most exposed men could be less fertile than the least exposed,” she said.
If you are wondering whether fathers’ alcohol consumption has any impact on their sons’ sperm quality, this study checked that, too. The scientists did not uncover any association between the fathers’ use of alcohol and semen volume or concentration.
Numerous studies have reported that male sperm counts around the world have fallen by more than 50 percent over the last 50 years. Some of the reasons given are poor diet, lifestyle habits, environmental factors (e.g., exposure to lead, phthalates, pesticides), and stress.
If further research supports the finding that a mother’s alcohol use during pregnancy may harm her son’s sperm, Ramlau-Hansen concludes that “then we are a bit closer to an explanation of why semen quality may have decreased during the last decades and why it differs between populations.” If fetal exposure to alcohol causes poor semen quality in adults, it seems likely that populations with many women drinking during pregnancy would have lower fertility rates compared with populations where pregnant women do not drink alcohol.
European Society of Human Reproduction and Embryology