In the US, one in eight couples, or 6.7 million peoplestruggle to conceive. A quick Twitter search of “IVF” will return scores of women sharing heartbreaking stories of failed IVF rounds and crushing miscarriages, like Breanna. Each year, the use of assisted reproductive technology (ART) increases 5-10%. Considering that our only real job, biologically, is to procreate, this is very alarming.
Probably the most popular (and controversial) work regarding infertility comes from Shanna Swan, an environmental and reproductive epidemiologist and professor at the Icahn School of Medicine at Mount Sinai. In her book Count Down, Swan finds that sperm count in Western men has dropped by more than 50% in the last forty years. Even more shocking, Swan predicts that by 2045, we’ll have a median sperm count of zero, and most people will have to use ART to reproduce. The cause of this “Spermageddon?” Swan points to weight, alcohol, smoking, and, most importantly, endocrine disruptors.
Endocrine disruptors are chemicals like phthalates, bisphenols (e.g. BPA), pesticides, and flame retardants, which are found in everyday items like plastic, food, clothes, and skincare. When we absorb them (through eating, breathing, applying lotions, and wearing clothes), these chemicals can mess with our hormones. For example, phthalates are known to lower testosterone which, in turn, lowers sperm production. Research shows that women with polycystic ovarian syndrome (PCOS)— the most common cause of female infertility— have higher levels of BPA in their bodies. Even exposure to these chemicals in small amounts can have major effects on the body, as delicate hormone levels are already controlled by only slight changes.
One of the most surprising things about endocrine disruptors is that they begin to affect the body in utero, via exposure to the mother. In a previous newsletter, I wrote about new research that found BPA-containing microplastics in human placentas. Not only is it terrifying to think about “cyborg babies” (babies made out of a combination of human cells and inorganic entities) being born, but scientists have also found that the chemicals in the microplastics have an effect on the fetus’sreproductive health. After all, a female fetus develops all the eggs she will have in her lifetime in utero. One studylooked at the effects of BPA in mice and found that it caused birth defects in the mice’s grandchildren; the first generation mouse’s BPA exposure disrupted its fetus’s egg development, resulting in chromosomal abnormalities in the next generation. This suggests that the effects of endocrine disruptors can be multigenerational. In male fetuses, exposures to endocrine disruptors like phthalates have been shown to result in smaller penis size and, in adulthood, lower count sperm.