Low levels of oxygen in the womb, which can be caused by smoking or conditions such as pre-eclampsia, may cause problems with fertility later in life, a study carried out in rats suggests.
The research, led by scientists at the University of Cambridge, England, found that exposing fetuses to chronic hypoxia (low oxygen levels) during development led to them having advanced aging of the ovaries and fewer eggs available.
Hypoxia in the womb can be caused by a number of factors, including smoking, pre-eclampsia, maternal obesity, and living at high altitude. The condition is already known to have potential long-term effects on the health of offspring, including increased risk of heart disease. However, this study, published today in The FASEB Journal, is the first time it has been shown to affect fertility.
To investigate the effects of hypoxia, researchers from the Metabolic Research Laboratories at the University of Cambridge placed pregnant female rats in reduced levels of oxygen (13%, compared to the standard 21% found in air). They then examined the reproductive tract of their female pups at a later age and found a decrease in the number of ovarian follicles in the reproductive tract.
“It’s as if low levels of oxygen caused the female’s ovarian tissue to age faster,” says Dr. Catherine Aiken from the University of Cambridge. “Biologically, the tissue appears older and the female would run out of eggs — in other words, become infertile — at a younger age.”
Although the research was carried out in rats, Aiken says there is every reason to expect that the findings could be translated to humans, as previous studies looking at hypoxia during pregnancy in relation to other conditions such as heart disease have been shown to be relevant in humans.