In many instances, when working with couples who have had a previous miscarriage, patients seem to put a lot of focus on female factors for infertility. Egg quality and hormone levels have an important role, so working on these factors is indeed very important. However, something that almost every couple overlooks are the male-factors that can contribute to miscarriage and infertility in general. If the quality of sperm cells is suboptimal, the risk for infertility and miscarriage is equally as high.
Lately, there have been some very high quality studies evaluating for a very specific parameter for sperm health and its connection to infertility and miscarriage rates. The sperm parameter is known as "Sperm DNA Fragmentation." It is the extent to which the DNA of each sperm cell is damaged. This is a test that is not routinely run for males to evaluate their fertility.
How does Sperm Quality Affect Miscarriage Rates?
A recently published review concluded that the higher the rate of sperm DNA fragmentation, the higher the risk for miscarriage rates. They explained that this is due to what is known as a "Late Paternal Effect." The faulty DNA of the sperm cell, as it is activated can lead to maturation and developmental issues in the later stages of embryo development, contributing to miscarriage likelihood.
Can Sperm Quality affect Fertility Rates?
Absolutely. Poor motility, morphology, or sperm counts can definitely lead to decreased fertility rates. However, if high rates of Sperm DNA Fragmentation itself can lead to decreased fertility is still in debate. Some reviews have found no relationship between high sperm DNA Fragmentation and fertility/pregnancy rates while other high quality studies and reviews have found a connection between high DNA fragmentation rates and lowered pregnancy rates. The hypothesis from these studies is that while a sperm cell with fragmented DNA is capable of fertilizing an egg, its deficiency in the genome leads to problems with the development of the embryo, leading to miscarriage.
Which couples are at the highest risk for Miscarriage?
The capacity of the human body to heal at a cellular level is incredible. A wonderful example of this is that a healthy and high quality egg actually can help repair damaged and fragmented DNA of a sperm cell. So in a couple where the ovarian reserve is normal or high and the Sperm DNA is fragmented, the risk for miscarriage increases only slightly.
But when the egg reserve is low, and egg quality starts to decline, such as after the age of 35, the ability of the egg to repair and heal damaged sperm DNA is limited. Couples where the egg is from a Woman with low ovarian reserve and the sperm has high DNA Fragmentation rates, may have the highest risk for miscarriage. In the recent review that was published, it was estimated that there is almost a 60% increased risk for miscarriage in these couples compared to couples with normal egg reserve and healthy sperm.