Smoking men expose the unborn to heart defects

Most people are likely aware of the adverse effects of smoking during pregnancy.

But discussions on this subject normally focus on the harms that a smoking mother can cause her unborn children.

As such, most campaign messages or doctors' recommendations during pregnancy largely target mothers who are advised to stop smoking.

This has led many to turn a blind eye to other individuals and second-hand smoke sources that could be detrimental to expectant mothers.

A new study published in the European Journal of Preventive Cardiology shows that fathers-to-be that smoke may increase the risk of congenital heart defects in their offspring.

The condition occurs when the heart, or blood vessel near it, fails to develop normally before birth.

The defects usually become evident soon after birth or during the first few months of life.

Signs and symptoms of the condition in newborns include fatigue, rapid breathing, poor blood circulation and a bluish tint to the skin, lips, and fingernails.

These congenital defects are a major cause of the 2.6 million stillbirths that happen globally each year, according to the World Health Organisation (WHO).

Stillbirths lead to more than 7,000 deaths daily, with the majority of these deaths (98 percent) occurring in low and middle-income countries like Kenya.

"Fathers are a large source of second-hand smoke for pregnant women. This smoke appears to be even more harmful to unborn children than women smoking themselves. So fathers-to-be should stop smoking, " said Dr Jiabi Qin, lead author of the study from the Xiangya School of Public Health at the Central South University in China.

Aside from looking at the impact of paternal smoking on the health of the unborn baby, the researchers also sought to analyse the link between maternal passive smoking (involuntary inhaling of smoke from other people’s cigarette) and the risk of congenital heart defects in offspring.

This was a first of its kind meta-analysis research (review of studies) to examine the effect of these different kinds of smoking on the heart of babies.

“Yet, smoking in fathers-to-be and exposure to passive smoking in expectant mothers are more common than smoking in pregnant women," stated Dr Qin.

Indeed, the study showed that the risk of congenital heart defects among children of smoking mothers was 25 percent.

But this figure shot to 74 percent and 124 percent among children with smoking fathers and those whose mothers involuntarily inhaled smoke from other people’s cigarettes respectively.

Second-hand smoke

In addition, the research results showed that women's exposure to second-hand smoke was risky for their offspring during all stages of pregnancy and even prior to becoming pregnant.

Those who smoked during pregnancy had a raised likelihood of bearing a child with a congenital heart defect, but smoking before pregnancy did not affect risk.

"Therefore, women should stop smoking before trying to become pregnant to ensure they are smoke-free when they conceive," said Dr Qin.

"Staying away from people who are smoking is also important. Employers can help by ensuring that workplaces are smoke-free."

According to Dr Qin, doctors and primary healthcare professionals need to do more to publicise and educate prospective parents about the potential hazards of smoking for their unborn child.

Aside from congenital heart defects, previous studies have shown that fathers-to-be can increase miscarriage risk among expectant women by smoking during the pregnancy, or even during the time leading up to conception.

A 2018 study published in the Journal of Epidemiology and Community Health found that women whose partner smoked during the first few months of the pregnancy were 17 percent more likely to miscarry than women with non-smoking partners.

The study from China, which was based on data for nearly six million pregnancies also showed that women whose partner quit smoking around the time of conception had an 18 percent lower risk of miscarriage than those whose smoking partner failed to do so.

A smoking partner or husband might influence the health of their unborn babies in two possible ways.

Quality of sperm

They can expose their wives or partners to chemicals through second-hand smoke that they blow out while smoking cigarettes, as well as third-hand smoke which refers to smoke deposits on clothes, furniture, carpets.

Alternatively, smoking might impact the quality of the father’s sperm, leading to genetic mutations that could in turn lead to birth defects in their offspring.

In a 2012 study published in the Federation of American Societies for Experimental Biology Journal, researchers found that men who smoke before conception can damage the genetic information in their offspring, leading to DNA mutations that make the children susceptible to fatal diseases like cancer in the future.

"It's for this reason that men should be urged to stop smoking before trying to conceive, in the same way women have been urged to quit," noted the researchers.

As fertile sperm take about three months to fully develop, men are thus advised to quit smoking long before they plan to 'make' babies or prior to conception.