© Shutterstock

Research -

Recent research suggests as little as one drink per week during pregnancy can affect a child's developing brain, face shape, cognitive function and behavior.

© Shutterstock

No safe amount -

Scientists have known for at least 50 years that drinking during pregnancy carries a risk and it's widely understood that there's no such thing as a "safe amount" of alcohol for expectant mothers.

© Shutterstock

Consensus -

While it's not clear what the effect is for light vs. heavy drinkers, there is a consensus among the scientific community that exposing a developing fetus to alcohol can cause a wide range of harm.

© Shutterstock

Fetal alcohol spectrum disorders (FASD) -

Fetal alcohol spectrum disorder (FASD) refers to a range of problems caused by exposure of a fetus to alcohol during pregnancy.

© Shutterstock

Fetal alcohol spectrum disorders (FASD) -

If a woman drinks alcohol while she is pregnant, the alcohol crosses the placenta from her blood into the baby’s bloodstream.

© Shutterstock

Harmful to the baby -

The effects on the baby include harm to the developing fetal nervous system, particularly the brain, malnourishment, and alterations in facial development, leading to distinct facial features.

© Shutterstock

Harmful to the baby -

There can also be speech delays in children who are born with FASD, as well as behavioral and learning issues. 

© Shutterstock

The role of the mother -

The role of the mother's alcohol consumption has been extensively studied in the past 50 years to understand the outcome it has on the baby's development.

© Shutterstock

How much the father drinks -

Now, experts are turning their attention to the amount of alcohol the father drinks, as this is something that has been overlooked.

© Shutterstock

How much the father drinks -

However, there have been many women over the years who claimed not to have drank during pregnancy who gave birth to a child with FASD. They tended to be dismissed as forgetful, or lying outright.

© Shutterstock

Discovering the link -

The idea that the amount a father drinks pre-conception could have an impact on the developing baby seemed too far-fetched to be considered.

© Shutterstock

New studies -

But a 2021 study from China observed that babies born to fathers who drank more are at a higher risk for several health issues.

© Shutterstock

New studies -

Where the father drank pre-conception, but the mother didn't drink, the risk of several kinds of birth defects was found to be much higher.

© Shutterstock

Congenital heart defects -

If the father drank more than 50ml (1.7fl oz.) of alcohol per day in the three months before pregnancy, babies were more than three times more likely to have a congenital heart defects.

© Shutterstock

Cleft palate -

In the same study, it was found that babies born with a cleft palate occurred at a rate 1.5 times higher to fathers who drank, than if the fathers didn't drink. 

© Shutterstock

Alcohol intake recommendation -

The researchers concluded that, to reduce the risk to the future baby, fathers should be encouraged to decrease their alcohol intake for three months before conception.

© Shutterstock

Alcohol intake recommendation -

Although the risk of overall birth defects is still relatively low regardless, the fact paternal drinking substantially elevates the risk means that it's something that should be considered.

© Shutterstock

Foetal growth -

A study published in July 2024 found a correlation between a father's drinking pre-conception and that it appeared to have impacted fetal growth. 

© Shutterstock

Other factors -

However, it's unclear whether this was the actual cause, or just associated with having an impact on fetal growth, as there could be other paternal behavioral contributors.

© Shutterstock

Other factors -

Lifestyle factors including nutrition, exercise, and whether or not someone smokes paint a wider picture of paternal health pre-conception, alongside alcohol consumption. 

© Shutterstock

Randomized control trials (RCT) -

Although carrying out an RCT on pre-conceiving couples and pregnant women involving alcohol wasn't a possibility due to ethical considerations, Michael Golding, a developmental physiologist at Texas A&M University, and his team researched FASD symptoms on mice to better understand the risks.

© Shutterstock

Randomized control trials (RCT) -

To map the abnormalities observed in FASD babies onto mice, the researchers divided the mouse "parents" into three groups: one group where only the pregnant mothers were given alcohol, one where only the fathers were given alcohol before conception, and one where both parents received alcohol.

© Shutterstock

Results -

Some FASD-associated facial patterns were more pronounced if the father drank compared to if the mother did, while overall growth and the facial pattern were worse when both parents drank.

© Shutterstock

Mitochondrial dysfunction -

Markers of mitochondrial dysfunction were discovered at midlife in the mice whose parents had both been exposed to alcohol.

© Shutterstock

Increased cellular aging -

Whether it was caused by mitochondrial dysfunction or not, increased cellular aging was also discovered in the liver and brain cells of the same mice.

© Shutterstock

Observational studies in humans -

The findings can help better our understanding of similar findings observed in humans with FASD. They tend to be hospitalized more frequently, and their life expectancy is 42% of that of the general population.

© Shutterstock

Observational studies in humans -

Of course, these effects still aren't as strong as when a mother consumes alcohol after conceiving, as this directly exposes the growing baby to the substance.

© Shutterstock

Higher brain functions -

However, there are still more significant findings. In mice whose fathers (but not mothers) were exposed to alcohol pre-conception, areas involved in higher brain functions were mixed up compared to mice where both parents weren't exposed to alcohol pre-conception.

© Shutterstock

Motor skills -

The motor and behavior skills of these mice also worked differently. They were clumsier and more hyperactive, and their learning was slowed.

© Shutterstock

Epigenetics -

Even though the growing mice hadn't been exposed to alcohol while they were in utero, certain parts of genomes are switched on and off without physical changes to the DNA sequence. This process is known as epigenetics and could be the answer.

© Shutterstock

Disruption to DNA methylation of sperm -

Alcohol has been observed to disrupt the DNA methylation of sperm. This might explain why changes in gene expression occur in the growing embryo. Chronic alcohol use has also been found to change the makeup of inherited fragments called RNA in sperm.

© Shutterstock

The father's role: not to be ignored -

While this is a growing area of research, it's posing an interesting question. The effect of the mother's alcohol consumption while pregnant, is undeniable. While more research is needed, emerging studies suggest the role of paternal health in the health of their offspring is something that can no longer be ignored.
Sources: (BBC Future) (NHS) 
See also: Is women's fertility more complicated than we've been led to believe?

© Shutterstock