If a couple of healthy twenty-year-old girl and boy have sex every two or three days without using contraceptive methods, their probability of pregnancy will be around 25% monthly. When you turn 30, that percentage begins to decline very slowly.
Although the man is responsible for about a third of cases of sterility in a couple, the advanced age of women is currently the main cause. From the age of 35, and especially since the age of 38, a woman’s chance of becoming pregnant plummets.
The key to this process is in the ovaries, those two almond-shaped organs show symptoms of premature aging at just 30 years. However, and despite the interest of millions of infertile women to have children, the difficulty in studying healthy ovaries has made these mechanisms remain an enigma.
Today, a team of scientists reveals the ins and outs of this phenomenon and opens the possibility of intervening and extending the fertility period in women beyond that natural limit.
Scientists have come to the Xieerxin Institute of Biological Resources, a Chinese center near Beijing that houses more than 4,000 monkeys used to experiment on issues such as fertility.
Scientists removed the ovaries from four macaques of about five years and another four females of about 20 years, ages that would be equivalent to 16 and 60 years in women.
The result is “the first thorough analysis of the aging of the ovaries in the area of a single cell in non-human primates”.
Macaques and humans moved away from a common trunk about 25 million years ago, compared to the 96 million years of evolution that separate people from mice.
There is a need to study aging in primates if we really want that knowledge to be transferred to the clinic,” says the report. Laboratory results achieved amazing results in recent months, such as the creation of human and monkey chimeras. Monkey embryo culture outside the uterus and the generation of artificial embryos from a single mouse-ear cell.
The team has studied 2,600 cells of the ovaries of the macaques with an unprecedented level of detail. The results confirm that oxidative stress – the harmful chemical reactions that occur when cells consume oxygen to generate energy – plays a key role in the aging of the ovaries.
The DNA of each cell is an instruction manual to build the proteins that carry out almost all the tasks of life. An intermediate molecule, RNA, allows you to read DNA and make these proteins.
The group of scientists studied all the RNA molecules of each cell, observing how the activity of genes changes at each stage of life. Researchers have observed that two genes, IDH1 and NDUFB10, possess antioxidant properties and shield some cell types of the ovary from oxidative stress. The passing of the years weakens this natural shield.
The results were confirmed with cells donated by women who have resorted to assisted reproduction techniques. The authors believe that these findings could also facilitate the diagnosis and treatment of infertility associated with ovarian aging, and even help fight diseases linked to this process, such as ovarian cancer.
Studies lay the foundations to evaluate the quality of the oocytes –the precursors of female eggs- and calculate the reproductive age of women.
Knowing the importance of oxidative damage can lead to antioxidant interventions to protect the ovary against aging and also to the development of tools to rejuvenate the oocytes and extend the fertility period of women.
The new study is the cover of the prestigious specialized magazine Cell, with an illustration of two monkeys in a tree that reflects a classic Chinese story about the search for the fountain of youth.
This work will leave hundreds or thousands of projects, said scientists. The problem of postponing maternity is not only in Europe and the United States, it begins to be one seen worldwide.
Our grandmothers had us when they were 20 years old; our mothers with 30; and now women are mothers at 40. This study opens the possibility of stopping the aging of the ovaries or even reversing it.
Males produce sperm throughout their lives, but women are born with a certain number of oocytes. From 35-38 years, the most defective remain and abortions or children with Down Syndrome increase.
It would be the dream of any clinician to give antioxidant supplements to young women who do not want to have children at the moment, to stop the aging of their ovaries. This is an investigation with great social implications, although, for the moment, it is daydreaming.