Giving Birth to Sons May Lower Mother’s Lifespan
According to Senior Researcher Samuli Helle, giving birth to boys lowered mother’s lifespan in pre-industrial time. Demographic data collected from Finnish parish registers kept by the Lutheran Church were used as research material.
The research states that giving birth to boys burdened mothers more than giving birth to girls. Giving birth to girls didn’t have a significant effect on parents’ lifespan. The effect of children on father’s lifespan was also studied but the sex of the child was insignificant.
– During the pregnancy, the bigger size of boys increases the energy need of the fetus. Also, during and after childbirth the larger size of baby boys compared to girls, burden the mother. Boys need for example more energy during breastfeeding, Helle says.
The Effects of Boys on the Mother Are Various
According to Helle, who works at the Section of Ecology of the Department of Biology, the reason for the lowered lifespan of mothers’ could also be hormonal.
The testosterone level of mothers’ who give birth to boys can be higher. It’s likely, that the testosterone weakens the immune system of mothers.
Two hundred years ago when healthcare and hygiene were poor, the weakening of mother’s resistance could have been fatal.
As Mothers Got Older, the Effect Decreased
– The more time passed after the latest childbirth, the better changes the mother had to grow old. The mother had plenty of time to recover from giving birth. On the other hand, the reasons can also be social. When boys grew up they were more of a help to the mother, Helle ponders.
Today’s Mothers Are Physically Stronger
Helle states that the research can’t directly be compared with the present.
– The people of the pre-industrial time did more physical work and the availability of nourishment was slimmer. Altogether, the society was so different that the physical stress of giving birth was much more severe to the mothers than nowadays, Helle emphasizes.
>> The research article on Biology Letters
Text: Jasmina Savolainen
Pictures: Hillary Moldovan, Jasmina Savolainen