For the first time, researchers have identified common defects in sperm that are linked to complications during pregnancy as well as potential negative effects on the health of the newborn. A study conducted by Lund University in Sweden reveals that a significant number of spermatozoa from fathers with DNA strand breaks are associated with a doubled risk of preeclampsia in women who conceive via IVF. Additionally, this condition raises the likelihood of premature birth.
Infertility is an increasing issue, and the frequency of in vitro fertilization (IVF) procedures is soaring. It is already established that women who conceive through assisted reproductive technologies are at a higher risk of developing preeclampsia, experiencing multiple miscarriages, and giving birth prematurely with lower birth weights. However, the underlying causes of these issues have yet to be fully understood.
“Prior to a planned IVF procedure, sperm samples from men are examined for various factors like concentration, motility, and morphology. However, some men may have normal results according to these tests and still face fertility challenges,” explains Amelie Stenqvist, a lecturer at Lund University, who previously earned her PhD there and is currently a specialist in gynecology and obstetrics at Skåne University Hospital in Malmö.
Research indicates that approximately 20-30 percent of infants conceived through IVF have fathers with sperm DNA that is damaged, evidenced by high levels of DNA fragmentation. The DNA fragmentation index (DFI) measures how many breaks are present in the DNA, offering critical insights into male fertility. While sperm with DNA damage can still result in fertilization, the overall chances diminish, especially if the DFI surpasses 30 percent, where the likelihood of natural conception approaches zero.
Despite the advancements in IVF techniques that allow men with significant DFI to father children, there has been limited understanding of how this DNA fragmentation influences pregnancy and the health of the newborn. The challenge in studying this issue arises from the fact that DFI is not typically measured by fertility clinics in Sweden, and research requires access to large populations and national health registries.
“Given that half of the placental DNA originates from the father and that the development and functionality of the placenta are crucial in preeclampsia, we wanted to explore if a high percentage of DNA damage in sperm impacts the risk of this condition,” states Aleksander Giwercman.
Giwercman is a professor of reproductive medicine at Lund University and a consultant at Skåne University Hospital in Malmö. He is also a key researcher in ReproUnion and was involved in a study that monitored 1,660 children conceived via IVF and ICSI at the Reproductive Medicine Centre in Malmö from 2007 to 2018.
The findings revealed that among the 841 couples who underwent IVF, a DFI exceeding 20 percent resulted in a doubled risk of preeclampsia (10.5 percent) and also increased the chances of premature delivery. In the IVF subgroup with a DFI below 20 percent, the preeclampsia risk was only 4.8 percent, similar to rates seen in spontaneous pregnancies. No links to preeclampsia were observed in couples undergoing ICSI.
“Currently, DFI analysis is only available at a select number of fertility clinics in Sweden, but we advocate for its routine implementation across all clinics. This analysis could provide couples with crucial insights regarding their difficulties in conceiving and may influence the selection of their fertility treatment. Furthermore, our recent findings indicate that DFI analysis could be instrumental in identifying pregnancies at higher risk,” emphasizes Aleksander Giwercman.
What makes this discovery particularly noteworthy is that elevated DNA fragmentation in sperm is indicative of the father’s overall health and may be treatable. Most DNA damage stems from oxidative stress, which occurs when there is an imbalance between harmful molecules and the antioxidants that guard cells. Other contributors to increased DNA fragmentation include the father’s age, smoking, obesity, and infections.
“The next phase is to determine which group of men would benefit most from strategies aimed at preventing and treating sperm DNA damage and to evaluate these approaches in the context of reducing pregnancy complications,” concludes Amelie Stenqvist.
