By Dr. Suchithra Reddy, Senior Consultant - Infertility Specialist, Rainbow Children’s Hospital, Sarjapur Road
Air quality has been a major factor in the classification of the lungs and the heart health problems, but infertility in both women and men is still a hidden thing that is all the more pronounced. There is a growing understanding of the damage that air pollution may cause to fertility and reproduction through the exposure to high pollution levels for a long time, especially in Indian cities, whereby the reproductive cells can be damaged and the hormones disrupted, among others pregnant complications being a risk. While pollution may not be the only reason at all, it is a significant contributor to the already existing reproductive problems.
Impact of Air Pollution on Male Reproductive Health
Male reproductive health has faced the most problematic situation ever caused by the combined effect of the polluted air and long-term exposure. The fine particulate matter that is so much talked about among other pollutants, especially PM2.5, has a direct role in the sperm count, sperm motility, sperm morphology and DNA fragmented quality, resulting in higher and larger being the case for the latter. The primary mechanisms responsible for these adverse effects are, as in the case of the latter, very similar; hence the damage is done by oxidative stress and inflammation, the two processes primarily affecting the spermatogenic cells of the seminiferous tubules that produce sperm. Heavy metals in the air can also play a role as they interfere with testosterone the male hormone that is crucial for sperm maturation.
Effects of Air Pollution on Female Fertility
Pollution in the air is another factor that can influence female fertility just like it does in males. An extensive review of studies has provided substantial evidence backing the claim that exposure to different pollutants during the process of conception lowers the chances of it being successful and increases the rate of miscarriage. Some of the common city air pollutants like PM2.5, nitrogen dioxide, and polycyclic aromatic hydrocarbons are reported to have a negative impact on the function of the ovary and also affect the implantation of the embryo. Apart from the very process of conceiving, air that is polluted results in a higher risk of pregnancy complications, such as premature birth, low birth weight, and others. This is mainly because the pollutants can fetter the flow of oxygen and nutrients to the embryo which is developing, thus leading to severe pregnancy outcomes
Hormonal Disruption Caused by Air Pollution
One of the leading pathways through which air pollution influences fertility is hormonal disruption. A large number of the substances that make up polluted air play the role of endocrine-disrupting chemicals, i.e. they affect the hormone's production, transport, and action. The fine particles, toxic gases, and heavy metals present in the air can either disguise themselves as the natural hormones, hinder the receptor's action or alter the function of the glands producing hormones. Air pollution exposure has been reported to result in the disturbances in the secretion of estrogen and progesterone, and modifies the levels of the ovulation-related hormones like FSH and LH, thus leading to the reduced ovarian function, poor egg quality, menstrual irregularities and increased risk of miscarriage. These alterations are interlinked and directly influence ovulation, implantation, and the viability of the early pregnancy.
A number of fertility-related impacts of air pollution are mediated by the two aforementioned biochemical pathways—chronic inflammation and oxidative stress. Inhaling of toxic air creates whole-body inflammatory responses that not only harm hormone-secreting organs like ovaries, testes, and thyroid but also impair the function of hormone receptors and the intercommunication between the brain and endocrine organs. These metabolic changes lead to hormonal imbalance and consequently, disrupt reproductive function. The degree of the effect differs from one person to another, and not all who are exposed to the pollution develop problems related to reproduction or hormones.
Understanding PM2.5 and PM10 Exposure
The risk of exposure to particulate matter can be described as a hierarchy of dangers. The risk of exposure to PM10 is lower than that of PM2.5 as PM10 mainly consists of larger particles that are filtered out in the upper airways while PM2.5 is made up of fine particles that are dangerous because they can easily penetrate deep into the lungs, get into the bloodstream, and then to hormone-producing organs like the ovaries, testes, and thyroid, thereby having even greater impact on reproductive health than when the exposure was only respiratory.
Early Pregnancy Risks
The issue of maternal exposure during early pregnancy is particularly critical. The first three months of pregnancy with higher pollution levels involve a very slight but real increase in the risk of abortion, especially in the case of daily exposure as opposed to single events. Additionally, one of the mechanisms through which pollution affects pregnancy is the impairment of placental development, which can lead to another complication of preeclampsia, growth restriction, and preterm birth because of reduced blood flow and heat. Even more, fetal development in terms of growth and lung formation has been affected albeit the risks are not certain but at the population level.
Air pollution is one of the factors that affect fertility in India, especially in cities. Although not being the main reason for infertility, air pollution exposure reduction can significantly enhance reproductive results, especially when it comes to IVF and early pregnancy, thus underlining the urgency of considering clean air as a reproductive health concern.
