Abstaining from alcohol during preconception and pregnancy is usually considered to be the woman’s responsibility. The main concern surrounding alcohol exposure during pregnancy often relates to well-established evidence of newborns developing a range of behavioral, physical, and cognitive disabilities later in life.
But recent research is also pointing to a link between alcohol and poor sperm development, meaning the onus is on expectant fathers too. A myriad of studies is showing biological fathers who drink alcohol may have a significant role in causing health problems in their children.
Studies are showing paternal alcohol consumption has negative effects at all levels of the male reproductive system, in addition to altered neurological, behavioral, and biochemical outcomes in subsequent generations.
Booze and Swimmers
In the latest Dietary Guidelines for Americans, the U.S. Department of Health and Human Services defines moderate drinking as up to two drinks per day for men and one drink per day for women.
According to that definition, one in three American adults drinks excessively. The rates are particularly high among men and younger adults, making younger men the most at-risk for this behavior.
These figures are alarming given the compelling evidence about the impact of excessive, chronic, or binge alcohol consumption on sperm, semen quality, fertility, and child health.
Animal studies have shown a single dose of ethanol into the stomach lining (equivalent to a human binge drinking) induces damage to the testis, damaging the cells essential for sperm formation.
In another experimental study, sperm health and fertility was assessed in male rats after the administration of alcohol into the stomach for 10 weeks. The results confirmed alcohol significantly reduced sperm concentration and the ability of the sperm to move properly. And none of the rats exposed to alcohol fertilized the females, despite confirmation of successful mating.
Studies in humans have also supported these findings. A recent study of 1,221 young Danish men, 18 to 28 years of age, tracked alcohol consumption in the week preceding the study to determine its effects on semen quality (volume, concentration, total count, and shape).
The results showed sperm concentration, total sperm count, and percentage of sperm with normal shape got worse the more the men drank. This association was observed in men reporting at least five units of alcohol in a typical week, but was most pronounced for men with a typical intake of more than 25 units a week. This suggests even modest habitual alcohol consumption of more than five units a week can negatively affect semen quality.
A recent review of studies and meta-analysis of population data replicated many of these findings. The main results showed daily alcohol intake at moderate to high levels had a detrimental effect on semen volume and normal shape.
The Effects on Children
Limited studies have tracked the drinking patterns of fathers around the time of conception and subsequent health outcomes of the child. But rodent models have shown changes in offspring weight and development, learning and activity, and anxiety-related behaviors, as well as molecular and physiological effects.
A study also reported that women whose partners consumed 10 or more drinks per week prior to conception had a two to five times increased risk of miscarriage compared to those whose partners did not drink during preconception.
Other studies provide some preliminary evidence that paternal preconception alcohol use is associated with acute leukemia at high-level use, heart malformation with daily use, microcephaly with low to moderate use, and effects in relation to fetal growth and mild cognitive impairments.
How Can Alcohol Affect Sperm?
The exact mechanism of how alcohol alters developing sperm and the later health outcomes of the fetus is still not yet fully understood. It’s been suggested alcohol can change the micro-environment within the testes, altering the development and maturation of the sperm.
It’s also been suggested that alcohol can influence sperm by creating genetic alterations and epigenetic marks. This means changes to gene expression occur without changes to the underlying DNA sequence. These epigenetic marks can be transferred at the time of fertilization. This can subsequently alter the molecular makeup of the early embryo, leading to alterations in fetal development and the potential to impair offspring health.
The biggest hurdle for researchers now is continuing to translate findings from the basic sciences to more sophisticated research in humans. The next stage is to identify patterns of alcohol use by men during the preconception period on fetal and childhood outcomes.
But most importantly, we need to realize decisions about alcohol use during the preconception period are not the sole responsibility of women. We need to be talking to men about these issues to ensure healthy outcomes for the baby.