If a man’s sperm has damaged or broken DNA, the embryo is more likely to develop problems with its chromosomes… even if the woman’s egg is completely healthy.
For far too long, the narrative around miscarriage has placed a heavy, often unspoken, burden of blame on women. In the raw aftermath of a loss, grieving mothers are often left with questions like, “What did I do wrong?” or “Is there something wrong with my body?”
Historically, doctors have focused intensive testing on the female partner, examining uterine anomalies, hormonal imbalances, and genetic factors within her biology. However, new research is revolutionising our understanding. For most early pregnancy losses, the cause may not be the woman’s body, but the quality of the man’s sperm. This is a critical, yet often overlooked, fact.
Let’s start with the fundamental biological reality: the vast majority of early miscarriages (50-80 per cent) are caused by chromosomal abnormalities in the embryo. This means the embryo received an incorrect number of chromosomes, too many or too few, or had structural defects in its genetic material, making it non-viable. Nature, in its wisdom, often ends these pregnancies early, as they cannot develop into a healthy baby.
Four miscarriages. Six babies lost. Then, a miracle in the ninth pregnancy.
Margaret Nyawira’s story is one of pain, faith and unimaginable endurance. For years, she fought through loss after loss, until the day she finally held her miracle child in her arms.
Sperms are not just passive transporters of half the genetic material
For decades, these chromosomal errors were largely attributed to the egg, especially as a woman aged. While maternal age is indeed a factor in egg quality, the narrative largely excluded the male contribution, creating a significant blind spot in both research and clinical practice.
Sperms are not just passive transporters of half the genetic material. Each sperm carries 23 chromosomes, meticulously packed within its head. When a sperm fertilises an egg, it contributes its chromosomes, along with other crucial cellular components, to form the complete genetic blueprint of a new human being. The quality of this genetic contribution from the sperm is paramount. If the sperm’s DNA is damaged or incorrectly packaged, the resulting embryo is far more likely to have a chromosomal abnormality, even if the egg is perfectly healthy.
The term “sperm quality” goes far beyond simple count and motility. Modern fertility science now focuses on key microscopic details:
- Sperm DNA Fragmentation (SDF): This is perhaps the most significant, yet frequently overlooked, factor. It refers to breaks or damage in the sperm’s genetic material.
- The Impact: When a sperm with high DNA fragmentation fertilises an egg, the egg tries to repair the damage. If the damage is too extensive, the repair fails, leading to miscarriage. Relevant studies show a strong correlation: couples where the male partner has high SDF rates experience significantly higher rates of pregnancy loss.
- Causes: SDF can be caused by oxidative stress (an imbalance between free radicals and antioxidants), infection, lifestyle factors like smoking, exposure to toxins, excessive heat, age and obesity.
- Aneuploidy in Sperm: Just as eggs can have an abnormal number of chromosomes, so can sperm. If a sperm carrying an extra or missing chromosome fertilises an egg, the resulting embryo will be non-viable and likely to miscarry.
- Epigenetic Imbalances: Beyond the DNA sequence itself, sperm carry epigenetic “marks” that act like dimmer switches on genes, regulating their expression. If these marks are imbalanced, they can negatively impact embryonic development, leading to early loss.
Consider this: In a relevant landmark review published in the journal Fertility and Sterility, researchers concluded that “abnormal sperm parameters, including high DNA fragmentation, are associated with increased rates of miscarriage.” They stated that for recurrent miscarriage, male factor issues are “underestimated and under-investigated.”
This scientific shift challenges the ingrained societal assumption that miscarriage is primarily a “woman’s problem.” After recurrent pregnancy loss, the woman often undergoes invasive testing, while the man might only receive a basic semen analysis that looks “normal,” completely missing crucial DNA fragmentation data.
The implications of this truth are profound.
Clinically:
- Targeted Interventions: If high SDF is identified, interventions like lifestyle changes, antioxidant supplementation, or medical treatment can significantly improve sperm quality and reduce future risk.
- Fertility Treatments: In assisted reproduction, high SDF can lead to poorer outcomes. Selecting sperm with lower DNA damage can be crucial for success.
Emotionally:
- Shared Responsibility: Recognising the male contribution helps destigmatise miscarriage for women, shifting the narrative from individual blame to a shared journey.
- Empowerment through Knowledge: For men, understanding their role can be empowering. It allows them to actively participate in improving fertility, which can be a relief for those who have felt sidelined.
The science is clear: male sperm quality is a significant, often primary, factor in early miscarriage. It’s time for this information to move from scientific journals into mainstream conversation.
If you or someone you know has experienced miscarriage, especially recurrent losses, here’s what to consider:
- Demand Comprehensive Male Fertility Testing: A basic semen analysis is not enough. Ask for a Sperm DNA Fragmentation (SDF) test.
- Lifestyle Matters for Both Partners: Men can significantly improve sperm quality through a healthy, antioxidant-rich diet, regular exercise, and avoiding smoking, excessive alcohol, and heat exposure.
- Advocate for Yourself: If your doctor is only focusing on female factors, gently but firmly inquire about advanced male factor testing.
The journey through miscarriage is heartbreaking, often shrouded in silence. By illuminating the profound role of sperm quality, we can empower couples with knowledge, foster a more balanced approach to fertility, and ultimately help bring more healthy babies home. The “fault” for miscarriage rarely lies with one partner, but the opportunity for understanding and intervention lies with both.
Dr Madeline Iseren is a Pharmacist and Essayist.
