Infertility

Infertility

In Canada, about one in six couples experiences difficulty conceiving a child. Infertility is defined as the absence of pregnancy after 12 months of regular, unprotected sexual intercourse. This issue can have multiple causes related to the woman, the man, or to social, biological, and environmental factors.

Within the RQR, several research teams focus on different aspects of infertility, both in males and females.

Male infertility 

In men, infertility can be caused by problems in the male reproductive system. The ducts that transport sperm cells, such as the vas efferens and the epididymis play an important role in male fertility. Sperm produced in the testicles leave the testis unable to swim or fertilize an egg. It is during their passage through the epididymis that they acquire these essential functions, thanks to a maturation process. This maturation depends on the luminal environment of the epididymis, shaped by several mechanisms, including pH regulation, secretion of sperm-binding proteins, and the action of the blood-epididymis barrier, which controls the selective passage of certain molecules through the epithelium. The development and specialization of this epithelium are therefore crucial to ensuring male fertility.

A disruption in the function of the vas efferens and the epididymis can prevent sperm from fertilizing the egg. Daniel Cyr seeks to better understand how the cells of the epididymis develop and specialize. This process, still poorly understood, is nonetheless essential for the organ to fulfill its role in male fertility. Sylvie Breton’s laboratory focuses on the physiology of the epididymis, an organ that is not only key to making sperm fertilization-competent but also to protecting them from the immune system. Clémence Belleannée’s team studies primary cilia—tiny cellular "antennas"—and their role in male fertility. This research also opens the door to developing new approaches in male contraception.

The interaction between sperm and egg involves a series of well-regulated steps that lead to fertilization. Pierre Leclerc’s work focuses on the process of capacitation, a transformation that sperm undergo after ejaculation while traveling through the female reproductive tract. This process alters their membranes, ionic balance, and enzyme activity, enabling them to fertilize the egg. Cristian O’Flaherty and his team aim to understand how sperm cells become capable of fertilizing an egg and how this process is influenced by certain molecules called reactive oxygen species (ROS). In large amounts, these molecules can damage sperm by affecting their DNA, movement, and ability to fertilize. However, in small quantities, they can play a helpful role by activating processes that make sperm functional. The team is also studying how the gut microbiome may affect male fertility.

Exposure to certain medical substances or environmental pollutants can also negatively affect fertility. Géraldine Delbès’s team investigates how these agents damage immature germ cells, which later develop into sperm. Bernard Robaire’s research focuses on the effects of environmental toxins on male fertility and on how aging affects the male reproductive system.

Some medical treatments, such as chemotherapy for cancer, also raise concerns regarding male fertility. Makoto Nagano’s team is working on techniques to preserve fertility in young boys undergoing such treatments. Their research focuses on spermatogonial stem cells (SSCs), which are present from birth and produce sperm throughout life.

Female infertility

In women, fertility is strongly influenced by age. Over time, the number of available eggs decreases and their quality declines. This is due in part to errors in cell division and chromosome distribution. Greg FitzHarris’s team studies the key factors that contribute to the health of human oocytes and embryos, with the goal of improving fertility treatments offered in clinics.

Recent studies have shown that some regions of the genome, once thought to be useless, may actually play important roles in reproduction. Jullien Flynn’s research focuses on satellite DNA and its functional impact on both male and female fertility.

Some rare variations in sexual development, such as sex reversal syndromes, provide valuable insights into how the body determines sexual characteristics and how this can affect fertility. Teruko Taketo’s lab investigates how sex chromosomes influence the reproductive potential of oocytes. Nicolas Pilon’s team studies, among other topics, CHARGE syndrome, which includes fertility issues and cases of male-to-female sex reversal.

To better understand reproductive disorders, Bernhard Payer’s team develops in vitro laboratory models. These tools allow researchers to explore human fertility mechanisms in greater detail and to model certain diseases, helping to improve the precision of treatments.

Jacquetta Trasler’s research focuses on how the environment—including diet, medications, and toxins we are exposed to—affects fertility.

Finally, beyond biology, Laurence Charton explores the sociology of reproduction. She studies how biosocial factors—such as cultural norms, life trajectories, access to healthcare, and economic conditions—influence fertility. These elements interact with biological determinants and are essential for a comprehensive understanding of reproductive pathways.