For couples trying to conceive, does alcohol consumption affect male fertility? As couples wait longer to have children, reproductive health researchers are increasingly studying male fertility. A new analysis of two studies of Danish and American couples has found that the amount of alcohol consumed by men attempting to conceive may not play a factor in their reproductive success.
Previous studies have shown a possible correlation between imbibing and male fertility, linking alcohol consumption with a negative impact on male reproductive hormones and the maturation of sperm. Small clinical studies found that alcohol consumption could potentially alter male reproductive hormones and spermatogenesis (the process by which sperm mature in the testes). But one study found that men who drank wine had stronger, healthier sperm.
For the new analysis, published in Human Reproduction Journal, scientists examined two ongoing studies of fertility and health in couples attempting to conceive, as a way to look at male alcohol consumption and reduced fecundability. (Scientists define fecundability as the likelihood of pregnancy within one menstrual cycle.)
The two studies were SnartForældre ("Soon Parents"), an ongoing prospective cohort study of 662 Danish couples that has been collecting data since 2011, and the North American Pregnancy Study Online (PRESTO), which is similar in design to SnartForældre and has followed 2,017 couples in the U.S. and Canada since 2013.
In both studies, the couples included were in a stable relationship with a partner of the opposite sex and attempting to conceive, and were neither using contraception nor receiving fertility treatment. SnartForældre recruited women ages 18 to 49 and men older than 18, whereas PRESTO recruited women ages 21 to 45 and men 21 and older. Both studies excluded couples that had a history of difficulty conceiving as defined by six or more months of attempting to conceive without success.
The studies tracked alcohol consumption, defining a serving as a 12-ounce beer, 4-ounce glass of wine or 1.5 ounces of liquor. Individuals were classified as drinking 0, 1 to 5, 6 to 13 and more than 14 standard servings per week. The studies relied on patients' self-reporting their alcohol consumption (which is not always reliable).
More than 1,700 women in the study became pregnant within a year, representing more than 64 percent of the couples, similar to past studies with women in this large age range. The average intake of alcohol by males on a weekly basis was 4.5 standard servings in the SnartForældre study and 4.1 in PRESTO. The data showed the differences in fecundability between men who drank 14 drinks a week or less was statistically nearly the same as men who didn't.
There were some differences between the two database samples. The males in the Danish study had higher rates of physical activity as well as of sexually transmitted diseases. The North American male participants, on the other hand, spent more time working, were more likely to have an elevated body mass index, and ingested more soft drinks. All of these are factors that can impact fertility.
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Even though researchers did not find a correlation between alcohol consumption and male fertility in this analysis, they caution that their research had some limitations, including that the analysis did not discern between types of alcohol. However, the data did mark a decreased fecundability in heavy drinkers who consumed more than 10 servings of beer or 6 of hard liquor per week. The study also considered alcohol consumption based on a weekly amount and did not differentiate between binge drinking and moderate drinking.
Although this study is encouraging for couples that engage in moderate drinking, other studies do point to lifestyle factors such as diet and smoking as important considerations for reproductive success. Any couple struggling to conceive should consult with a medical professional.