Sperm Morphology and Male Fertility (Episode 469)

Full Transcript: Episode 469

Lisa Hendrickson-Jack: Welcome to the Fertility Friday Podcast, your source for information about the Fertility Awareness Method and all things fertility. I’m your host, Lisa Hendrickson-Jack. I’m the author of The Fifth Vital Sign and the Fertility Awareness Mastery Charting Workbook. I’m a certified fertility awareness educator and holistic reproductive health practitioner with over 20 years of experience teaching women to connect to their fifth vital sign through menstrual cycle charting, balancing hormone health, and optimizing the menstrual cycle without hormones.

I’ve been outspoken about hormonal birth control and its impact on fertility and overall health because you have the right to know how your body works. I teach women’s health professionals how to use the menstrual cycle as a vital sign, and I host coaching programs to support fertility and cycle health. This podcast is designed to empower you to take control of your cycles, fertility, and overall health.

As a follow-up to last week’s episode on sperm quality and declining sperm parameters, I’m sharing a replay of a previous conversation with Professor Thinus Kruger. His research played a key role in the standardization of international sperm morphology guidelines by the World Health Organization. In this episode, we discuss sperm quality, morphology, motility, count, and the factors that influence male fertility.

Lisa Hendrickson-Jack: I’m very happy to be here today with Professor Thinus Kruger. Professor Kruger is the founder of the first IVF clinic in South Africa and a co-founder of Aevitas Fertility Clinic. He led the team at Tygerberg Fertility Clinic responsible for the first test-tube baby, the first frozen embryo pregnancy, and the first baby born from ICSI in South Africa, as well as the research that informed WHO sperm morphology guidelines.

Professor Thinus Kruger: Thank you. It’s an honor to be here.

Lisa Hendrickson-Jack: You’ve been at the forefront of assisted reproductive technologies, but I invited you specifically to talk about sperm morphology. What led you to focus on fertility challenges, and particularly sperm morphology?

Professor Thinus Kruger: I’m a gynecologist with a long-standing interest in male infertility. In the 1980s, male factors were often neglected. During laparoscopic procedures, we observed sperm inside the female reproductive tract and noticed that a specific sperm shape appeared repeatedly. When we compared this with raw semen samples, we saw a wide variety of shapes.

Working with my colleague, Dr. Menkveld, we observed that the sperm found in the female body often had a head shaped like an acorn. We stained, measured, and counted these sperm and began to study whether morphology influenced fertilization. At the time, I was completing my PhD, and one of the areas I wanted to study was male contribution to IVF outcomes.

We observed that men with very low percentages of normally shaped sperm had much lower fertilization rates, while men with higher percentages had significantly higher fertilization rates. Statistical analysis confirmed a clear relationship between morphology and fertilization.

Lisa Hendrickson-Jack: So you found a connection between sperm shape and fertilization and pregnancy rates?

Professor Thinus Kruger: Yes. At that time, morphology was widely considered irrelevant. Count and motility were believed to be the important factors. Our work challenged that assumption and showed a stepwise improvement in fertilization as morphology improved.

Lisa Hendrickson-Jack: How did this research translate beyond South Africa?

Professor Thinus Kruger: I later completed a fellowship at the Jones Institute in Virginia. There, poor fertilization was often attributed to egg factors. I suggested conducting a blind prospective study focusing on morphology. The results mirrored our earlier findings. We were able to predict fertilization outcomes based on morphology alone, which surprised many colleagues.

We described different morphology patterns, including poor prognosis patterns and normal patterns, each associated with different fertilization rates. These findings further reinforced morphology as an important factor.

Lisa Hendrickson-Jack: What does this mean for couples trying to conceive naturally?

Professor Thinus Kruger: Low morphology does not mean a man cannot conceive. I never tell a patient that pregnancy is impossible. It may take longer, but natural conception can still occur. Fertility always involves both partners. It truly takes two to tango.

Lisa Hendrickson-Jack: There’s often an assumption that if conception doesn’t happen, the issue lies with the woman.

Professor Thinus Kruger: That assumption is common and inaccurate. Male factors play a significant role and must be evaluated alongside female factors.

Lisa Hendrickson-Jack: You’ve also discussed lifestyle and environmental influences on sperm quality.

Professor Thinus Kruger: Yes. Research and observational models, including animal studies, suggest diet, environmental exposures, and lifestyle factors influence sperm morphology. We’ve seen associations with diet quality, environmental toxins, and overall health.

Lisa Hendrickson-Jack: Is there a relationship between sperm morphology and DNA integrity?

Professor Thinus Kruger: There is. Studies have shown that sperm with abnormal morphology are more likely to have DNA fragmentation. Even with technologies like ICSI, sperm selection remains important because DNA integrity affects embryo quality.

Lisa Hendrickson-Jack: You’ve mentioned that the female reproductive tract also plays a role in sperm selection.

Professor Thinus Kruger: Cervical fluid helps filter sperm, favoring those with normal morphology. This natural selection process supports healthier sperm reaching the egg.

Lisa Hendrickson-Jack: What should couples know about semen analysis and lab variability?

Professor Thinus Kruger: Morphology assessment requires specialized training. Some labs may be overly strict. Second opinions can be valuable, and low morphology should not automatically lead to invasive interventions.

Lisa Hendrickson-Jack: When are men considered subfertile versus infertile?

Professor Thinus Kruger: Subfertility refers to reduced parameters, not sterility. True sterility is diagnosed only after repeated findings of no sperm. Many men classified as subfertile can still conceive.

Lisa Hendrickson-Jack: Is there anything you’d like to leave listeners with?

Professor Thinus Kruger: Focus first on foundational factors. Address lifestyle and overall health before moving to advanced technologies. Many couples can conceive naturally when these factors are optimized.

Lisa Hendrickson-Jack: Thank you so much for sharing your time and insights. This has been a valuable conversation.

If you enjoyed today’s episode, you can find the show notes at fertilityfriday.com/469. I’ll continue highlighting the importance of sperm quality and male factor fertility whenever possible. Until next time, be well and happy charting.