The work, led by Dr Myriam Hemberger at the Babraham Institute and the Centre for Trophoblast Research in Cambridge, UK, is one of the first to look at the effects of age on womb health and it is expected to lead to new research into human pregnancies.
The risks of complications during pregnancy all increase with age. A woman in her late 30s is twice as likely as a younger woman to have a stillbirth, she is also 20% more prone to giving birth prematurely and more likely to experience conditions such as pre-eclampsia.
By examining first pregnancies in aged mice, the team showed that, for mice as for humans, the risk of complications increases with age. Closer examination revealed that the wombs of older mothers are less able to support the growth of a placenta, meaning the developing young have poor blood supply, which slows their growth and can cause birth defects.
Co-first author Laura Woods said when they compared mice, who have their first litter in middle age, to their younger counterparts, they found that the lining of the uterus does not respond as well to pregnancy hormones and this delays placenta formation. By identifying the key pathways affected by age in mice they have a better idea of what to look for in humans.
Hemberger said: "Overall, our study highlights the importance of the ageing uterine environment as a cause of reproductive decline in female mice. This is one of the first times that the considerable impact of age on pregnancy has been studied in detail beyond the effects of egg fitness. More research will be needed to establish if and how our results translate to humans."
The study appears in Nature Communications. (ANI)