Is Climate Change Affecting Birth Rates?
Using data from the US, two early studies demonstrate that higher temperatures reduce birth rates approximately nine months later, for every day over 80 degrees there will be 10,000 fewer births in the USA populations! Heat stress negatively affects ovaries by inhibiting follicular growth and oocyte quality. In the context of climate change, more hot weather is going to hinder people’s ability to have a child. Multiple studies show that sperm production falls in the weeks after a hot spell. Pregnant people are more likely to experience heat stroke and heat exhaustion, according to the CDC. High temperatures can increase risks of stillbirth and preterm birth. And experts worry that state officials may scrutinize such pregnancy outcomes more closely in the wake of the June 2022 Supreme Court decision overturning the constitutional right to abortion. The irony is the same people who rally for the right to life are ignoring the existential threat of climate and its role in births.
Climate change raises the stakes even higher. Hot days are already more common around the globe. Heat waves are hotter and last longer than they were in the past, increasing the risk of heat-related illnesses and death. Reductions in sperm and decreases in testosterone in males caused by heat stress have been evident lab tests. When it's hot, the scrotum relaxes and the testicles settle lower, and, as all men know, when it's cold, they rise up and are held close to the body. From the body's attempts to protect itself from temperature changes and its effects on the motility and amounts of sperm we can conclude that heat exposure is a significant risk factor for male infertility. In fact a persons amount of melanin is important in that the sperm of the male and the egg of the woman both are layered with melanin. So when the sperm penetrates the egg, there is a melanin explosion. This helps to formulate the fetus. This fetus is literally coated with this melanin substance. Melanin is the catalyst for birth!
Human skin pigmentation is the product of two clines (traits) produced by natural selection to protect our ability to procreate. One cline was generated by high Ultra Violet Radiation (UVR) near the equator and led to the evolution of dark, photoprotective, eumelanin-rich pigmentation. The other was produced by the requirement for UVB photons to sustain cutaneous photosynthesis of vitamin D3 in low-UVB environments, and resulted in the evolution of depigmented (colorless) skin. Extreme UVA throughout the year and two peaks of UVB prevail within the tropics. UVB damages skin cells and causes DNA mutations that can eventually lead to melanoma and other types of skin cancer.
Under these conditions, the primary selective pressure was to protect folate by maintaining dark pigmentation. Folate is the natural form of vitamin B9 in food, while folic acid is the synthetic form. Folate is found mainly in dark green leafy vegetables, beans, peas and nuts. Fruits rich in folate include oranges, lemons, bananas, melons and strawberries Essentially foods very prevalent in tropical diets. Folate is essential for healthy births. Folate can have a powerful effect on female fertility, both before and after conception. For women who are struggling to conceive, a lack of folate can cause pregnancy defects that can lead to miscarriage and cognitive issues. Folate is sensitive to photolysis which is depletion of folate caused by exposure to UVR.
Exposure to sunlight and UVR in particular causes lower folate levels and decreases likelihood of a healthy birth. Competition for folate between the needs for cell division, DNA repair, and melanogenesis (creation of melanin ie. tanning) is severe under stressful, high-UVR conditions . The populations exhibiting maximally depigmented skin are those inhabiting environments with the lowest annual and summer peak levels of UVB. Depigmented and tannable skin evolved numerous times in hominin evolution via independent genetic pathways under positive selection. In high UV environments such as the tropics or a planet that has had its climate warmed and increased…Extreme levels of UVR can be detrimental to depigmented birthrates. This is especially a concern for people who use bleaching products, as they may end up being infertile because of products that lighten the skin and cause it to lose its natural protective barrier, making it vulnerable.
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