The Effects of Advancing Paternal Age on Pregnancy
As women age, the number and quality of their eggs decline and rates of chromosomal abnormalities increase making it increasingly harder to have a successful pregnancy. While these effects are well documented in the literature, the effects of paternal age on in vitro fertilization (IVF) and neonatal outcomes are less known. Based on this information, Dr. Sydney Chang, a senior reproductive endocrinology fellow at RMA of New York, hypothesized that a higher prevalence of chromosomal abnormalities in embryos from men with advanced paternal age could be associated with early pregnancy loss. Using single, chromosomally normal frozen embryo transfers from donor eggs, Dr. Chang found that there is no correlation between paternal age and risk of miscarriage, preterm delivery, or low birth weight.
To learn more about the impetus for her study, “The Effect of Advancing Paternal Age on Pregnancy and Neonatal Outcomes Following a Single Euploid Frozen Embryo Transfer in a Donor Oocyte Model,” and the impact the results can have on future patient care, we sat down with Dr. Chang and asked her to further elucidate this novel research.
1. Can you discuss the previous study performed by RMA of New York that found no association between paternal age and impaired fertilization or increased chromosomal abnormalities? How did it inspire this subsequent study?
Because men are constantly producing new sperm, it has long been thought that advancing paternal age does not affect the chromosomal content of embryos in the same way that advancing maternal age does. However, some studies of chromosomal abnormalities in human sperm have shown an increased incidence of abnormal chromosomal copy number, especially involving chromosomes 21, 22, X, and Y. We wanted to see if there was a higher incidence of chromosomal abnormalities in embryos as paternal age increased. After controlling for the age of the egg donor, we found that there was no statistically significant impact on IVF outcomes or rate of chromosomal abnormalities with increasing paternal age. While this was reassuring, we wanted to look deeper and see whether advancing paternal age increased miscarriage rates or had any neonatal effects, such as preterm birth and low birth weight.
2. Why did you decide to use frozen donor egg-derived embryos for this study?
We chose to use donor eggs (oocytes) because we wanted to look specifically at the paternal contribution. Using eggs from young donors makes it much less likely that the egg is a contributing factor. We only looked at cycles where a single, chromosomally normal, embryo was replaced so that we could eliminate confounding factors that may affect implantation and miscarriage rates.
3. Are there any follow-up studies currently underway?
In the future, we would like to study how paternal age impacts what genes are turned on and off in the developing embryos and understand how this may affect pregnancy outcomes and newborn health and development.
4. How do the results of this study affect RMA of New York patients? Can this have an impact on clinical care in the future?
Our patients can feel reassured that we have shown that there is no increased rate of chromosomal abnormalities, miscarriage, preterm birth, or low birth weight as a result of transferring embryos created using sperm from older men. These results may be useful for counseling patients who may be considering the use of donor sperm to decrease the effects of advancing paternal age.