With commentary by lead study author Karen Moritz, PhD, associate professor at the School of Biomedical Sciences, University of Queensland, Australia
Most women know to stop drinking during pregnancy because of the risks to their developing fetus. But a new study shed light on the risk of women drinking alcohol while trying to conceive. The study on laboratory rats found an increased risk of type 2 diabetes in the offspring of rats that were given alcohol around the time of conception.
The authors began to think about the effects of alcohol during the time of conception, since many women of reproductive age drink socially. “It is well known that alcohol can have effects on the fetuses during development,” says Moritz. Many women stop drinking as soon as they are aware that they are pregnant. “We wondered, however, if there may already be some effects of the alcohol on very early embryonic development.”
Moritz fed the rats the equivalent of five drinks during a period four days before conception until day four of gestation. They found that the offspring had elevated fasting glucose, impaired glucose tolerance, and decreased insulin sensitivity at six months of age. Together these raise the risk that they would develop type 2 diabetes and obesity in early middle age.
“Before the egg implants, before any organs start to develop, alcohol consumption somehow causes changes to the embryo,” says Moritz. “We think the alcohol exposure around conception has caused changes in the very early embryo. This may be changes in expression of genes necessary for normal development or the metabolism of the embryo."
The researchers also wanted to compare the effects of alcohol to the effects of a high fat and sugar diet, like the typical Western diet, which when consumed by pregnant women, has also been associated with an increased risk of type 2 diabetes and obesity. They placed some offspring, both control animals and those exposed to alcohol, on a Western diet when they were young adults. They found that the degree of insulin resistance (a precursor to diabetes) was similar in control rats (no alcohol) exposed to a Western diet and those exposed to alcohol but on a non-Western diet.
“This suggested that alcohol exposure around the time of conception was equally able to induce insulin resistance as consumption of the high fat diet in adult life,” says Moritz.
The study is the first to show an effect of alcohol consumption around conception on metabolism in offspring, but it is preliminary. “This study demonstrates the association, but it is important to remember that it is an animal model, “says Siobhan Dolan, MD, MPH, medical advisor to the March of Dimes. “So now it needs to be tested in women.” In the meantime, Dr. Dolan recommends women trying to conceive skip alcohol. “There are many reasons to abstain from drinking alcohol when you are trying to conceive or are pregnant, and this is yet another,” she says.