Men should avoid consuming alcohol for six months before trying for a baby to ensure that their child has a healthy heart, according to the first large-scale analysis to examine the role of paternal drinking. The research, published on Thursday in the European Journal of Preventive Cardiology, found that fathers drinking three months before conception increased the risk of congenital heart disease in babies by 44 per cent, while this risk was 16 per cent for mothers, compared to not drinking.
There was a 52 per cent higher likelihood of these birth defects if fathers indulged in binge drinking -- defined as five or more drinks per sitting -- while this risk was 16 per cent for mothers, researchers said.
"Binge drinking by would-be parents is a high risk and dangerous behaviour 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 Central South University in China.
Qin said the results suggest that when couples are trying for a baby, men should not consume alcohol for at least six months before fertilisation while women should stop alcohol one year before, and avoid it while pregnant.
Congenital heart diseases are the most common birth defects, with about 1.35 million babies affected every year.
These conditions can increase the likelihood of cardiovascular disease later in life, even after surgical treatment, and are the main cause of perinatal death.
Alcohol is a known teratogen -- which causes malformation of an embryo -- and has been connected with foetal alcohol spectrum disorder (FASD), researchers said.
Around one in four children with FASD have congenital heart disease, indicating that alcohol might also be implicated in these disorders, they said.
Previous studies investigating the link between alcohol and congenital heart disease have focused on prospective mothers, with inconclusive results.
This is the first meta-analysis to examine the role of paternal alcohol drinking, researchers said.
They compiled the best data published between 1991 and 2019, which amounted to 55 studies including 41,747 babies with congenital heart disease and 297,587 without.
The analysis showed a nonlinear dose-response relationship between parental alcohol drinking and congenital heart diseases.
"We observed a gradually rising risk of congenital heart diseases as parental alcohol consumption increased. The relationship was not statistically significant at the lower quantities," Qin said.
Regarding specific defects, the study found that compared to abstinence, maternal drinking was correlated to a 20 per cent greater risk of tetralogy of Fallot, a combination of four abnormalities in the heart's structure.
The researchers noted that this was an observational study and does not prove a causal effect, nor does it prove that paternal drinking is more harmful to the foetal heart than maternal drinking.
The data cannot be used to define a cut-off of alcohol consumption that might be considered safe, researchers said.
"The underlying mechanisms connecting parental alcohol and congenital heart diseases are uncertain and warrant further research," Qin said.
"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," he said.