Making headlines on news platforms including BBC and Time, the decline of male fertility has stimulated discussion in both scientific literature and dinner table conversations. Associate Elizabeth Kemp conducted an interview via email with Dr. Hagai Levine, MD, MPH, who is the lead researcher and Head of the Environmental Health Track at the Hebrew University-Hadassah Braun School of Public Health; Adjunct Assistant Professor at Mount Sinai, NYC. Levine's recently published article, “Temporal trends in sperm count: a systematic review and meta-regression”, has inspired questions regarding what declining male fertility signifies for the developing world.

Elizabeth Kemp (EK): What is your background and how did you find yourself researching male fertility?

Dr. Hagai Levine (HL): As a physician and epidemiologist, I was always interested in the larger picture and in prevention, and public health residency was the right path for me. My last role in the IDF was as Head of Epidemiology Section and I gained a lot of experience in studying trends and focusing on health of young men and women. Besides being a passionate public health practitioner, I am a curious scientist, so I joined the faculty of the Hebrew University-Hadassah Braun School of Public Health.

The impact of the modern environment on our health is a crucial, understudied field, and when I met Shanna Swan from Mount Sinai in Israel in 2009 I realized that male reproduction is very affected by the environment, both during fetal development and in adult life. Male fertility is essential for our survival, is an important marker of our general health and is a great model to study the impact of environment on our health. It is also one of the most fascinating field to study – the essence of life, but yet remained a largely neglected field. Well – this is the field for me. I had the chance to come as a visiting scientist to Mount Sinai, New York in 2014 and collaborate with Shanna Swan and others on studying the impact of modern environment on male fertility.

EK: In a September 2017 Newsweek article discussing the male infertility issue specifically in the U.S. you were quoted saying that, “reproduction may be the most important function of any species.” If part of our reproduction system is beginning to fail, how can we grapple with that?

HL: First, we should recognize that male reproduction is a major public health problem. The first step would be to direct research toward studying the causes and implications of male reproduction problems, which includes semen and sperm quality and function (in the macro and micro levels), testicular germ cell tumors, congenital malformations such as cryptorchidism and hypospadias, and hormonal problems such as low testosterone. In parallel, we should prevent harm to the developing (fetal) and developed (adult) male reproductive system by, for example, better regulation of endocrine disrupting chemicals and pesticides and better health promotion efforts including tobacco control and obesity prevention.

EK: Do you see the same rates of declining male fertility globally and if not what could be the cause for some of the difference in fertility rates?

HL: We found dramatic decline in sperm count among Western men. Sperm count is an important measure of male fecundity and a marker of general health. Male fertility is not monitored and we have poor data to assess trends of male fertility per se. Fertility rates (of women) declined in Western countries, due to many reasons, and the contribution of decline in male fecundity is unknown. We know even less regarding non-Western countries, and we did not have enough data to conclude regarding sperm count trends in non-Western countries. We should set surveillance systems to monitor male and female reproductive health.

EK: How will declining male fertility affect the population globally?

HL: We already have a problem, as shown by the large proportion of couples having problem in naturally conceiving. Effects on the fertility of the entire population may be seen later in time. However, the decline in sperm count implies that we live in an environment that is unhealthy for men's health and reproduction. We don't know yet how this environment impacts the sperm molecularly (such as epigenetic changes) and how it will impact next generations.

EK: Designer babies are genetically modified embryos. Do you predict with decreasing male fertility an increasing rate of “designer babies?” Thus do you foresee an economic barrier to having children as a possible problem in the future?

HL: We should shape the future, not predict it (“The best way to predict your future is to create it” ― Peter F. Drucker). Economic barriers already [affect] fertility in many countries.

EK: How might the finding of decreased male fertility impact the healthcare fertility and birth control industry?

HL: This is already a growing industry. However, technological solutions to fertility problems may be justified on the personal level but are not sustainable at the population level. We must identify the causes of male and female fertility problems and prevent them.

EK: How will decreased male fertility affect social and cultural environments? Will there be a explicit, visible change in either male or female behavior (i.e. could it manifest itself on college campuses in the future)?

HL: Some suggested that from now man will bring their sperm count results to a date (or on [a] dating application). There is literature, in animal and human studies, on the [importance] of healthy looking (implicating high chances of being fertile) for mating choice. There is slow cultural change toward more emphasis on the role of the father in conception and reproduction. There is [a] “biological clock" for both men and women.

EK: Is there anything else you’d like to add?

HL: Subfertility may manifest as longer time to conceive. So this is a spectrum and it is actually pretty common to have longer time to pregnancy. I think we have a clear and present problem right now with men's health and fertility, and many people already experience some difficulties. If we ignore the problem, it will not go away. It will take very long time to fix the problem we created, so we should start now. We may encounter a "vicious cycle" and the rate of decline may actually increase. I don't want predict the future but we must take it very [seriously] and act now. The end may come closer than we think. My father, Prof. Ely Levine taught me to hope for the best, but be prepared for the worst. Personally, I am very worried from the impact of our modern world, with the many new chemicals we introduced to it the first time, on our fertility, our health and our environments, including our friends – the animals.