When couples are trying for a baby, men should abstain from alcohol at least six months before fertilization and women at least one year, according to new research.

When compared to abstinence from alcohol, fathers who drank in the three months leading up to conception saw a 44 percent increased risk of their child developing congenital heart disease (CHD). When it comes to binge drinking, defined by five or more drinks per sitting, men saw a 52 percent increased risk of their offspring developing a number of birth defects. For mothers, that risk was just 16 percent in both cases.

“Binge drinking by would-be parents is a high risk and dangerous behavior that not only may increase the chance of their baby being born with a heart defect, but also greatly damages their own health,” said study author Jiabi Qin, from Xiangya School of Public Health, in a statement.

Alcohol is a teratogen, an agent that causes the malformation of an embryo, and has been connected with fetal alcohol syndrome. About one-in-four children with fetal alcohol syndrome will also have CHD. It is the most common birth defect, affecting 1 percent of all live births and making it the leading non-infectious cause of infant death.

Previous studies have focused on a child’s risk of such disorders by way of their mother’s alcohol consumption leading up to and during pregnancy, but have largely produced inconsistent results. To analyze a father’s associated risk, the team conducted a meta-analysis of data from 1991 to 2019 from 55 studies of more than 41,000 babies with CHD and nearly 300,000 without. Across these studies, they searched for associated keywords like “congenital heart disease” or “cardiovascular malformation” and compared them against alcohol exposure.

They found that as a father’s alcohol consumption increased, so did his offspring’s likelihood of developing CHD, but the relationship was not “statistically significant at the lower quantities”. A mother’s drinking led to a 20 percent greater risk of tetralogy of Fallot, a combination of four abnormalities in the heart structure that results in blue-tinged skin color. Furthermore, CHD is concurrent in almost three-quarters of cases of FAS.

The authors are also quick to caution that their study does not prove that a father’s drinking is more harmful than the mother’s. Neither does it determine a hard point in time in the months leading up to conception by which either parent should stop consuming alcohol. CHD is a condition that is influenced by a variety of factors, including chromosomal anomalies, maternal illnesses, and prenatal exposures to toxins or therapeutic drugs.

“The underlying mechanisms connecting parental alcohol and congenital heart diseases are uncertain and warrant further research,” said Quin. “Although our analysis has limitations – for example, the type of alcohol was not recorded – it does indicate that men and women planning a family should give up alcohol.”

Published in the European Journal of Preventive Cardiology, the findings add to a growing understanding of how alcohol affects pregnancy and could help to inform public health implications as well as guide future health education on associated risks.