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Studies have repeatedly linked maternal smoking during pregnancy with reduced sperm count in children. A team of researchers from Lund University in Sweden discovered that, regardless of the mother's exposure to nicotine, men whose father smoked at the time of pregnancy had half as much sperm as those whose father was a non-smoker.
The study was conducted on 104 Swedish men aged 17 to 20 years. Once the researchers had adjusted to account for the mother's exposure to nicotine, socioeconomic factors and smoking of sons, men whose father smoked had 41% sperm concentration lower and 51% less sperm than men whose father is a non-smoker. The research team from Lund University is the first to report this discovery.
"I was very surprised that, regardless of the level of exposure of the mother to nicotine, the sperm count of men whose fathers smoked was much lower." says Jonatan Axelsson, medical specialist in occupational medicine and the environment.
The cotinine biomarker is a metabolite of nicotine that can be measured in the blood. By measuring cotinine levels, researchers can see if the parents themselves are smoking or have been exposed to pbadive smoking. Many previous studies have shown that it is detrimental to the fetus if the mother smokes, but in this study, the link between father's smoking habit and the sperm count of the son is even more clear.
Jonatan Axelsson can not explain why this is the case. and think that more research is needed to understand the underlying mechanisms. On the other hand, he explains, similar studies have also shown links between fathers smoking and various health problems in children, such as malformations.
"Unlike the maternal egg, the father's gametes divide continuously throughout life, and mutations often occur during life-a precise moment of cell division. tobacco smoke contains many substances that cause mutations, so we can imagine that at the time of conception, the gametes have undergone mutations and thus transmit genes that lead to a decrease in sperm quality in the offspring males. "
Most new mutations (called de novo mutations) occur via the father and there are also links between the father's age and a number of complex diseases. In addition, researchers have observed that smoking was related to damage of DNA in sperm and that smokers had more breaks in the DNA strand. Children of smoking fathers would have up to four times more mutations in a repetitive portion of the DNA than children of non-smoking fathers.
"We know that there is a link between the number of sperm and the chances of pregnancy, so it could affect the ability of these men to have children in the future." Father's smoking is also linked to a shorter reproductive life span for girls, so the notion that everything depends on whether or not the mother smokes does not seem convincing.The research could perhaps bring us closer to a causal link " Jonatan Axelsson concludes.
Explore Further:
Nicotine use by the father can cause cognitive problems in children and grandchildren
More information:
Jonatan Axelsson et al. Association between paternal smoking at the time of pregnancy and sperm quality in sons, PLOS ONE (2018). DOI: 10.1371 / journal.pone.0207221
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