Today’s society increasingly delays the age at which men become fathers. Many studies have already been conducted on this issue and on how a woman’s age affects many factors, including perinatal, obstetric and, of course, gestational outcomes. However little or nothing was known until now about the influence of paternal age in this regard.

Study of the influence of advanced paternal age

This issue is what gave rise to the studies submitted to this year’s Congress of the European Society of Human Reproduction and Embryology (ESHRE). The two studies, “Paternal Age Does Not Affect Obstetric and Perinatal Outcomes in IVF or ICSI Cycles with Autologous Oocytes” and “Paternal Age is Significantly Related to the Type of Delivery and the Sex of the Newborn in IVF or ICSI Cycles with Donated Oocytes,” were both led by IVI Foundation researcher Dr. Ana Navarro, and were supervised by IVI Foundation Director Dr. Nicolás Garrido. The aim of the two studies was to establish whether the semen of men with advanced paternal age may adversely affect the obstetric health of women during pregnancy. Another objective of the studies was to determine how much of an effect it has in terms of influencing the type of delivery and the health of the newborn.

As Dr. Garrido explains: “To do so, we have taken into account a series of pregnancy and perinatal health indicators such as gestational diabetes, hypertension, child weight, type of delivery, head circumference or admission to the ICU after birth, resulting in the conclusion that paternal age does not affect obstetric and perinatal outcomes in assisted reproduction treatments with own oocytes. At this point, and despite the fact that several studies suggest the threshold of 40 years for considering paternal age as ‘advanced’, we believe it is convenient to revise this limit according to current results”.

Is there a loss of quality due to advanced paternal age?

The aforementioned study examines whether there is any loss of sperm quality or even a decline in male fertility due to age. It also examines whether this would affect obstetric and perinatal outcomes in any way. However, after adjusting for maternal age and many other variables, the results do not show or reflect anything statistically significant when treatment is with the patient’s own and not donated oocytes.

Dr. Navarro states: “One of the reasons for this difference between men and women is purely biological: in men, spermatogenesis takes place constantly, every day and at all times, and therefore new cells are generated. Women, on the other hand, have follicles in their ovaries from when they are in their mother’s womb, i.e. they are with them all their lives. And, obviously, this influences the characteristics of fertilisation and all that it entails afterwards, as the sperm are not as old as the eggs when fertilisation is attempted”.

Paternal age and its influence on donated oocytes

Moreover, having studied not only treatments with the patient’s own oocytes but also donated oocytes, we are able to standardise the female factor. This is because the profiles are similar in terms of age and there is no history of health problems, etc. On this occasion, after studying pregnancies with donated oocytes, a slight variation was observed in the type of caesarean delivery and the sex of the newborn. This variation remained significant after appropriate adjustments were made. Despite this, nothing clinically relevant was observed, since, for example, the type of caesarean delivery is a variable that is influenced by medical or personal decisions at the time of delivery.

“Starting from the premise that advanced paternal age is understood to mean a male of at least 40 years of age, in the case of older ages, it is the medical problems associated with ageing that lead to the quality of the semen not being optimal and that can lead to a somewhat higher risk of disease in the baby, although these are very rare. Male fertility is still a somewhat unknown field in scientific terms, which is why at IVI, with this in mind, we continue to research on a daily basis to tackle the challenges it presents”, concludes Dr. Garrido.