The number of sperm is 50% lower among sons of fathers smokers: study

One study found that the number of men who smoked at the time of their partner's pregnancy is 50% less than that of their peers.

The study conducted by researchers from the University of Lund in Sweden was conducted on 104 Swedish men aged 17 to 20 years.

Once the researchers had adjusted for maternal exposure to nicotine, socioeconomic factors, and smoking of sons, men whose fathers smoked had a lower sperm concentration of 41% and 51%. % less sperm than men whose father was a non-smoker.

"I was very surprised by the fact that, regardless of the mother's exposure to nicotine, the sperm count of men whose father smoked was much lower," Jonatan said. Axelsson, from Lund University.

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 harmful to the fetus if the mother smokes but, in this study, the connection between smoking in the father and the sperm count of the son is even clearer, said researchers.

Axelsson can not explain why this is the case and thinks more research is needed to understand the underlying mechanisms.

On the other hand, 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," said Axelsson.

"We know that tobacco smoke contains many substances that cause mutations, so one can imagine that at the time of conception, the gametes have undergone mutations and thus transmit genes that cause a decrease in the quality of the semen in male offspring, "he said.

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 sperm count and chances of pregnancy, which could affect the ability for these men to have children in the future," Axelsson said.

"Father's smoking is also linked to a shorter reproductive life span for girls, so the idea that everything depends on whether or not the mother smokes does not seem convincing. closer to a causal link, "he said.