March 9, 2023 – Excessive alcohol consumption in the first week of pregnancy poses risks to the unborn child. However, a new study by Serge McGraw, epigenetics researcher and reproductive biology specialist at CHU Sainte-Justine, indicates that a healthy diet rich in nutrients, such as folic acid, vitamin B12, choline and betaine, could help reduce some of the effects of excessive alcohol use, particularly for people who do not yet know they are pregnant.

The results of the study were published early March in The FASEB Journal, the flagship publication of the Federation of American Societies for Experimental Biology.

Risks throughout pregnancy, even in the first week

Alcohol use at any stage of pregnancy can lead to a range of consequences falling under the umbrella of fetal alcohol spectrum disorder (FASD). These consequences, ranging from mild to very severe, include birth defects, growth retardation during pregnancy and emotional and behavioural problems related to brain development. Prenatal alcohol exposure affects an estimated 0.9% of children in North America. However, it remains very difficult to diagnose after birth.

Few studies have investigated alcohol use during the preimplantation phase of embryo development, i.e., in the first week of pregnancy when the embryo is floating freely in the uterus and pregnancy tests cannot yet detect fertilization. Unborn babies are particularly vulnerable at this stage. Until recently, it was mistakenly believed that embryos exposed to high concentrations of alcohol in this period would either undergo spontaneous abortion or develop properly. This is known as the “all-or-nothing effect.”

The work of Serge McGraw, who is also an associate professor at Université de Montréal’s Faculty of Medicine, dispels this belief. 

Using mice as models, his team had previously demonstrated in a 2021 study that embryos survive a single excessive dose of alcohol in the first week of gestation and exhibit morphological defects in 19% of cases. These abnormalities, which appear early during gestation and persist over time, have also been confirmed in the current study, but represent only a small proportion of the effects of alcohol use during pregnancy.  Indeed, “in our two studies on mice models, embryos with and without morphological defects also showed abnormalities in the mechanisms controlling gene expression, particularly in genes related to brain development,” explained Serge McGraw. Thus, for the normally developing embryos, it is very likely that many will have brain development issues after birth. In humans, 90% of children with FASD have no physical defects, but develop intellectual, emotional or behavioural symptoms later in childhood and adolescence.

Supplements that may protect unborn babies from the effects of alcohol

All this evidence suggests that people of childbearing age should be very cautious about drinking alcohol. “The only way to prevent the teratogenic effects of alcohol in unborn children is to avoid drinking alcohol, but we must find other safeguards for women who don’t yet know they’re pregnant,” added Serge McGraw. He and his research team have shown that a diet rich in nutrients such as folic acid, vitamin B12, choline and betaine, important for the epigenetic mechanisms that control gene expression, provides some measure of protection for embryos exposed to alcohol. In the study, mouse fetuses whose mothers were on such a diet before and during gestation had almost three times fewer morphological defects. Their skulls were closer to the expected dimensions and they had fewer and less varied morphological defects.

This study suggests that national dietary and alcohol guidelines for people of childbearing age or wishing to become pregnant should be changed.