Birth rates decrease all over the world. In all European countries it even goes down below Population replacement levels, which refers to the number of children needed per woman to maintain a stable population. While these declines may be due to many adults deliberately putting off having their first child—or actively choosing not to have children— A growing number of studies indicate These do not fully explain the low birth rates. Some research also indicates that reduced fertility is a major factor contributing to this decline.
One factor associated with reduced fertility is the presence of industrial chemicals present in our environment. Much is known about the effect of these chemicals on male fertilityHowever, little research has looked at how it affects women. This is what our latest study sought to do.
We found that exposure to common chemical pollutants was associated with Low number of eggs in the ovaries of women of childbearing age. Although these chemicals have since been banned, they were used in household products like flame retardants and mosquito sprays, and are still found in the environment and in foods like fatty fish.
We measured levels of 31 common industrial chemicals, such as HCB (an agricultural fungicide) and DDT (an insecticide), in the blood of 60 women. To measure their fertility, we measured the number of immature eggs present in the ovaries by counting them in ovarian tissue samples using a microscope. Because the ovaries are located inside the body and access to them would require surgery, we selected pregnant women who had undergone caesarean section, as this allowed access to tissue samples without additional surgery.
We found that women who had higher levels of the chemicals in their blood sample also had fewer immature eggs left in their ovaries. We found significant links between reduced egg counts and some chemicals, including PCBs (used in refrigerants), DDE (a byproduct of DDT) and PBDE (a flame retardant). As is female fertility by ageWe made sure to adjust our accounts according to the age of the woman in question. This showed us that exposure to these chemicals reduced the number of eggs in women of all ages.
We also found that women with higher chemical levels in their blood had to try to get pregnant longer. For the women with the highest levels of the chemicals in their blood, it took more than a year.
Unlike men, women are only born with a A fixed set of immature eggs In the ovaries, they cannot produce new ovaries after birth. A woman’s “reserve” (the number of eggs in her ovaries) naturally decreases through monthly ovulation, as well as through the death of the natural follicle. When depleted below a critical level, natural fertility ends and old age Begins. Our findings suggest that toxic chemicals may accelerate the disappearance of ovarian follicles, which may lead to reduced fertility and early menopause.
they were exposed to industrial chemicals Through our food, the products we put on our skin, and even through our mothers while they were growing in the womb.
The number of industrial chemicals, as well as their abundance in the environment, is steadily It has increased since the forties – With devastating effects on EcosystemsAnd the wild animals even human fertility. Several chemicals have been introduced to the market with A little safety test. This has led to a situation in which humans and the environment are exposed to a widespread “soup” of industrial chemicals.
So far, many chemicals have been found to be harmful to reproduction after only decades of consumer use. These include PFAS (the chemical used in Teflon, Scotch-Guard, and firefighting foam), Phthalates (used in plastic packaging, medical equipment, soap and shampoo) as well as Insecticides and others industrial chemicals Like a PCB.
Negative effects include Low sperm count Men have the ability, and women may be able to I got pregnant. Our study is the first to look at the link between exposure to chemicals and the number of eggs a woman has.
All of the chemicals we studied were “persistent,” which means that they build up in the body over time. Remarkably, the chemicals that we found to be associated with reduced egg counts were restricted to international treaty decades ago. after because of their persistenceThey still pollute the ecosystem and our food.
Interestingly, PCBs (one of the chemicals we studied) have also been associated with decreased sperm count and Male infertility. The simultaneous decline in male and female fertility may make it more difficult for couples to conceive.
In the future, researchers should investigate whether the fertility of all women – as opposed to pregnant women – is similarly affected by these chemicals. But these findings may encourage us to rethink chemical safety to take fertility into account during safety assessments. Avoid certain foods (such as SeafoodAnd some products (like the ones we put on our skin and hair) may also help reduce the negative effects of chemicals on our chances of having a baby.
Yasmine Hassan |PhD candidate in reproductive medicine, Karolinska Institute; Paulina Damdemopoulou, Senior Researcher, Chemicals and Female Fertility, Karolinska Institute, And the Richelle Duque BeurvangPhD candidate in reproductive medicine, Karolinska Institute