What if you got your period every three months? Hongmei Wang, the biologist investigating how to extend fertility

Biologist Hongmei Wang, who was born 52 years ago in the autonomous Chinese region of Inner Mongolia, is confronting a gigantic problem, equipped only with the humble weapon of scientific investigation. The researcher at the State Key Laboratory of Stem Cell and Reproductive Biology Laboratory in Beijing works on understanding the first stages of human development, a subject that has become crucial in a country immersed in the worst demographic crisis on the planet.

Many Western democracies are dealing with the same issue, to which no solution has yet been found. Aging populations and low birth rates threaten to collapse public health systems due to shrinking workforces and the growing costs of caring for citizens that are growing older and sicker. In China, the problem has reached monstrous proportions. For several years, the most inhabited country in the world has been losing its population. Despite the government’s new policies to raise birth rates, residents have been hesitant to have more children. If current trends continue, the country’s population could be halved by the end of the century, an unprecedented demographic collapse, according to the United Nations.

Wang was born in 1973 and has two siblings, which is unthinkable for any Chinese citizen born just six years after her or later. In 1979, Communist dictator Deng Xiaoping promoted the one-child policy as a response to the country’s growing worries about overpopulation at the time, when it was still finding its way out of poverty. The strategy was devised by Song Jian, a specialist in rocket and missile design who applied the cold logic of mathematics and engineering to his country’s societal challenges.

Today, China has the opposite problem. Though its government started allowing families to have two children in 2015, and three in 2021, population rates have not responded. The laboratory where Wang works, which during the years of the one-child policy was known as the Family Planning Laboratory, is now dedicated to investigating human reproduction and embryonic development in order to discover new ways of extending reproductive periods.

One of the options it is exploring is delaying menopause. It’s a possibility, according to the results of Wang’s studies on mice, but the scientist warns that such a prospect could be a double-edged sword. “If we inhibit ovulation, we can preserve available eggs, but at the same time, we inhibit the production of estrogen, which is a very important molecule for health,” Wang points out in an interview with EL PAÍS she gave a few days after arriving in Spain to participate in a scientific conference organized by Pompeu Fabra University in Barcelona.

Her words illustrate a complex challenge. In a single ejaculation, there can be 70 million spermatozoids. In contrast, a woman is born with a finite number of available eggs — around 400 — that will only be functional from puberty to menopause. Pushing back the arrival of menopause for even just a year “would have huge social importance,” says the biologist and embryologist.

Her team has made significant advances in the extension of fertility. In one fundamental study published last year, scientists injected human stem cells into the ovaries of sterile monkeys. The procedure resulted in the birth of a baby monkey, who is alive and healthy to this day, Wang notes proudly.

The scientists also carried out a small clinical trial with 63 women who suffer from premature ovarian failure, a condition that leaves individuals infertile in the middle of their reproductive years. Stem cell transplants enabled four of them to have healthy children, Wang says. Her team has patented its methods and licensed them to a private company.

Wang also wonders if it is possible to allow women to have their period every three months, which would preserve part of their healthy and available eggs in order to get pregnant. The idea remains an unknown that is for the moment, being explored via experiments on mice.

The Chinese scientist recognizes that there is still a lot we don’t know when it comes to the early stages of embryonic development, due to technical and legal challenges. Two weeks after a spermatozoid fertilizes an egg, the embryo begins the enigmatic process in which hundreds of almost-identical cells begin the precise choreography of creating a three-dimensional plan for a body, and the seeds of all organs. The soundtrack to this dance is inscribed on our DNA, but we still don’t know how cells know exactly what to become.

This process, called gastrulation, is one of the biggest unknowns in the field of biology. In part, this is due to the difficulty of getting discarded human embryos from the right stage to research, given that at two weeks, the vast majority of women don’t yet know that they are pregnant, which leads to many embryos being lost.

Another considerable barrier is legal. The majority of countries ban the cultivation of human embryos in the laboratory beyond 14 days, which makes gastrulation impossible. But that may soon change, predicts Wang. China and other countries are already preparing for an adjustment of regulations to allow for the cultivation of human embryos up to 20 or 28 days, which would allow for the complete window of gastrulation. That’s important, because no one knows why around half of all fertilizations fail. It’s possible that the explanation lies exactly in that crucial week in which the body and future organs begin to take shape.

Wang is collaborating with Pompeu Fabra University professor Alfonso Martínez Arias on the creation of embryonic models using human stem cells. These organoids allow for the simulation of natural embryos, and for the study of their development without legal hurdles. One of Wang’s goals is to recreate three essential organs when it comes to the development of a new human being: the ovary, embryo and placenta. The latter has not been paid enough attention, she says. “Just before birth, the placenta contains some 58,000 cell nuclei and measures 172 square feet. There is no other structure in the body that is as large that forms part of an organ,” she says.

The scientist is aware that her research is still in a preliminary phase, and that its results may not come quickly enough to halt her country’s demographic disaster. Also, that some of these experiments transcend the limits of science. “It’s one thing for something to be possible from the technical perspective, like delaying menstruation or extending reproductive life, and another for people to actually want for it to be carried out,” she concludes.

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