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Studies have repeatedly linked maternal smoking during pregnancy with reduced sperm count in male 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 among 104 Swedish men aged 17 to 20 years. Once the researchers had adjusted for maternal exposure to nicotine, socioeconomic factors, and smoking in sons, men whose fathers had smoked had a lower sperm concentration. 41% and 51% less sperm than men whose father is a non-smoker. The research team at Lund University is the first to report this discovery.
"I was very surprised by the fact that, regardless of the mother's exposure to nicotine, the sperm count of men whose fathers smoked was so much lower," says Jonatan Axelsson, medical specialist in occupational medicine and environmental medicine.
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 passive smoking. Many previous studies have shown that it is detrimental to the fetus if the mother smokes but, in this study, the connection between the 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 thinks 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 at the precise moment of cell division.We know that tobacco smoke contains many substances. that cause mutations, so we can imagine that at the time of conception, the gametes mutated and thus transmit genes that lead to reduced sperm quality in male offspring. "
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. It is reported that children of smoking fathers have up to four times more mutations in a repetitive portion of DNA than children of non-smoking fathers.
"We know that there is a link between the number of sperm and the chances of pregnancy, which could affect the ability for these men to have children in the future." also linked to a shorter reproductive life span for girls, so the idea of whether the mother smokes or not does not seem convincing.Possible future research could perhaps bring us closer to a link causality ", concludes Jonatan Axelsson.
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Material provided by University of Lund. Note: Content can be changed for style and length.
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