What happens if you drink and don’t know you’re pregnant?

According to new research from scientists at the Université de Montréal, the effects of rapid alcohol exposure early in pregnancy – when a woman drinks as many as six drinks per hour – can be detected in the placenta.

The study was led by Serge McGraw, associate professor and researcher at UdeM at the university-affiliated children’s hospital, CHU Sainte-Justine, and published in Environment International.

Using a mouse model well suited to alcohol exposure, McGraw and his team observed significant molecular changes in the placenta, including the expression of numerous genes and DNA methylation, an epigenetic marker that influences gene expression by acting as a switch.

Because the placenta plays a central role in the development and health of the fetus, these changes can have major consequences for the future of the child, the UdeM scientists believe. The study also shows that these DNA methylation changes may provide a robust molecular signature for detecting alcohol exposure during early pregnancy.

This proof of concept, the scientists say, paves the way for the development of diagnostic tests in humans, allowing early detection of alcohol exposure from the very first days of a newborn’s life.

Brain development is affected

It was long thought that exposure to alcohol during the pre-implantation phase, when the fertilized egg transitions from a one-celled to an embryo of about a hundred cells, had no effect on the unborn baby, provided the embryo managed to develop. implant in the uterus.

But in recent years, McGraw’s team has shown that this is not the case. The young embryo can survive this exposure, but brain development can be altered to varying degrees, they have found.

The new research shows for the first time that the harmful effects of alcohol on the development of the fetus are not directly due to abnormalities in the placenta. Molecular changes, especially in gene expression due to changes in DNA methylation profiles, could play an important role in these deleterious effects.

Interestingly, the epigenetic impact of alcohol exposure varies by gender, the study found.

In male embryos, the regulation of growth-related genes was more affected, confirming data showing that males are more vulnerable to growth retardation after preimplantation alcohol exposure.

In women, it was mainly the regulation of genes involved in the metabolism of serotonin, an essential neurotransmitter for brain development and function, that was affected.

This suggests that disruption of this signaling pathway could contribute to the brain morphological defects observed in the mouse model.

Six drinks in an hour

The research is based on high alcohol consumption: the human equivalent of five to six drinks per hour. The scientists say this makes it particularly relevant as around half of all pregnancies are unplanned and alcohol consumption among women is increasing worldwide, according to the World Health Organization.

“Our model tries to reproduce and understand the effects of a situation in which a woman, about a week pregnant, and therefore carrying an embryo of only a few cells, quickly consumes a large amount of alcohol – for example at a party or in a bar – without necessarily knowing she is pregnant,” McGraw said.

Although these results have yet to be confirmed in humans, the team believes that DNA methylation profiles could be a good indicator of whether a baby has been exposed to alcohol during pregnancy.

“There is currently no molecular diagnostic test for prenatal alcohol exposure,” says McGraw.

“So, unless a child is very seriously affected, the problems often go unnoticed until school age or even adolescence. For example, these young people may have concentration or behavioral problems that can hinder their progress at school.”

A screening test based on this molecular memory of exposure, found in the placenta, would ensure appropriate medical follow-up from an early age, he added.