In this episode you will uncover the pressing effects of declining fertility rates on the human population, delve into the influence of environmental factors, specifically exposure to harmful chemicals, on reproductive health, gain insights on age, egg/sperm quality, and environmental influences in fertility, grasp the effects of phthalates on male reproductive health, highlighting AGD and sperm count, and also realize the importance of increased awareness, research, and action to safeguard human health and fertility.Dr. Shanna Swan is an Environmental and Reproductive Epidemiologist. She is Professor of Environmental Medicine and Public Health at the Icahn School of Medicine at Mount Sinai, New York, Adjunct Professor in Obstetrics and Gynecology at the University of California San Francisco and Senior Scientist at Environmental Health Sciences. Dr. Swan's work examines the impact of environmental exposures on reproductive health and neurodevelopment. Links for this episodehttps://www.shannaswan.com/https://twitter.com/drshannaswanhttps://www.instagram.com/drshannaswan/https://www.shannaswan.com/countdownEpisode Overview00:07:32 - Population Decline, The world's fertility rate has dropped from over five children per couple to under two now, and a large proportion of the world is now below replacement. 00:12:17 - The Roller Coaster of Fertility, The declining fertility rate in many countries means that we are headed towards a maximum world population, which will decrease and never come back. 00:15:37 - Social Causes of Fertility Decline, The decline in fertility is not just due to social causes like women entering the workforce and getting educated, but also due to environmental and lifestyle factors. 00:22:28 - Environmental and Lifestyle Factors Affecting Fertility, Environmental and lifestyle factors, such as exposure to phthalates and Bisphenol A, are major contributors to the decline in fertility. 00:16:51 - The Challenges of Motherhood and Fertility, Dr. Stephanie and Dr. Shanna discuss the challenges of motherhood and fertility. The decline in egg quality and sperm quality with age is a major limiting factor in infertility, which is a concern for women who choose to have babies later in life. 00:19:57 - Decline in Male Fertility, Dr. Shanna explains that research on the declining rate of male fertility has been around for 30 years. The first study in 1992 reported that sperm count had decreased by 50% in 50 years. However, this figure was met with skepticism. 00:23:30 - Early Puberty in Girls, Dr. Stephanie brings up the phenomenon of early puberty in girls, and Dr. Shanna explains that it is a real concern. Girls are starting menstruation earlier and earlier, which is not only a risk for psychological and social challenges but also for fertility. 00:25:46 - Environmental Factors Affecting Sperm Count, Dr. Shanna discusses her study on environmental factors affecting sperm count. She found that exposure to phthalates, a chemical found in plastics, is linked to lower sperm count. Exposure to other chemicals like bis00:34:10 - Factors Affecting Sperm Count, The recruitment bias and selection bias of the men in the studies from 1940 and 1990 were analyzed. The lifestyle factors of smoking, obesity, exercise, and stress were found to be important. Chemicals that affect the reproductive system, particularly testosterone and estrogen, were also identified.00:40:16 - Plastic Increase and Endocrine-Disrupting Chemicals, After World War II, scientists were revered, and plastic production increased rapidly. However, plastic has a large number of chemicals that can alter hormones. Phthalates are particularly concerning as they lower testosterone levels and can affect genital formation during pregnancy.00:43:45 - Non-Monotonic Dose Response and Endocrinology, Hormones often respond non-linearly to low doses of chemicals, affecting not just testosterone, but also estrogen and the immune system. Endocrine-disrupting chemicals can hav