Paternal Age and IVF Miscarriage: Why Young Donor Eggs Did Not Erase the Difference

In 1,606 donor-egg treatment cycles, miscarriage rates were 25.4% with male partners over 45 versus 15.6% at 45 or younger.

Live birth rates were 34.3% versus 42.4%, suggesting that sperm aging deserves attention alongside egg age.

Paternal age was associated with miscarriage and live birth after donor-egg IVF in a study published in Human Reproduction on October 6, 2026. Even when eggs came from young donors, male partners over 45 had higher miscarriage rates and lower live birth rates than those aged 45 or younger.

Female age and egg quality have long been emphasized in fertility treatment. This research suggests that male age may also relate to pregnancy maintenance and birth when the contribution of egg aging is reduced.

Juan J. Fraire-Zamora and colleagues at Spain's EUGIN Group conducted the study.

An analysis of 1,606 donor-egg cycles

The researchers reviewed 1,606 donor-oocyte IVF cycles carried out at seven fertility centers between 2019 and 2023.

Recipients had an average age of 43.2 years, donors 26.2 years and male partners 43.1 years.

Using donor eggs helped reduce the influence of egg age on the analysis.

In conventional treatment, partners often age together, making it difficult to distinguish contributions from egg aging and sperm aging to pregnancy failure or miscarriage.

Young donor eggs offer a way to examine paternal-age associations with less influence from egg aging.

Only ICSI cycles were included. The analysis focused on the first single-blastocyst transfer to reduce variation in treatment conditions.

Miscarriage rates of 25.4% versus 15.6%

The researchers compared male partners aged 45 or younger with those over 45.

There were 1,031 in the younger group and 575 in the older group.

Miscarriage rates differed clearly.

Among partners aged 45 or younger, 81 of 518 clinical pregnancies ended in miscarriage, a rate of 15.6%.

Among partners over 45, 67 of 264 clinical pregnancies ended in miscarriage, a rate of 25.4%.

The difference was 9.8 percentage points.

After accounting for recipient age, donor age, body mass index, embryo grade and other factors, the reported adjusted association for miscarriage in the older group was approximately 1.86-fold relative to the younger group.

The result suggests that factors associated with increasing paternal age may affect pregnancy maintenance.

Live birth rates were also lower

Differences extended beyond miscarriage.

Live birth rates were 42.4% in the group aged 45 or younger and 34.3% in the group over 45.

Live birth measures whether transfer ultimately results in the birth of a living baby. It differs from a positive pregnancy test or visualization of a gestational sac on ultrasound.

The absolute difference was 8.1 percentage points.

The older group remained less likely to achieve live birth after statistical adjustment for other potential influences.

Interestingly, there were no clear age-group differences in the number of fertilized eggs or embryos reaching the blastocyst stage.

This suggests that fertilization and development to blastocyst do not capture every biological factor relevant to implantation, pregnancy maintenance and birth.

The study did not directly analyze embryo chromosomes or sperm DNA damage, so it cannot attribute lower live birth rates to genetic changes in sperm.

Age 45 is not a biological cliff

With increasing female age, egg numbers and quality decline and chromosome abnormalities become more likely. Men can continue producing sperm at older ages, which can create an impression that reproductive capacity remains unchanged.

Continued production does not necessarily mean that sperm retain the same biological condition.

Sperm DNA damage, new genetic variants and oxidative stress may change with male age. Sperm count and motility alone do not fully characterize these processes.

The present study did not directly test whether such mechanisms explained the increase in miscarriage.

An additional analysis divided paternal age into under 35, 35–40, 40–45 and over 45. The likelihood of live birth tended to decline as age increased.

The differences in miscarriage and live birth were most evident in the group over 45.

That does not mean there is no risk through age 45 followed by a sudden change at 46. Male reproductive aging varies between individuals and may progress gradually.

Fertility counseling should consider both partners' ages

The study suggests that paternal age should not be considered only in terms of sperm count or motility.

Normal semen parameters do not establish that every biological factor required after fertilization is normal.

For older men, previous pregnancies and miscarriages, other medical conditions and lifestyle may also be relevant alongside conventional semen results.

Older age alone does not mean that sperm DNA testing or additional procedures are automatically necessary. Testing and treatment depend on the individual clinical context.

This was a retrospective observational study. Its findings came from donor eggs, ICSI and single-blastocyst transfer and should not be assigned unchanged to natural conception or every conventional IVF cycle.

The association also does not prove that age directly caused miscarriage; other influences cannot be completely excluded.

Nevertheless, the study supports broadening a discussion that has often focused chiefly on female age and egg quality.

Couples delaying parenthood may need to consider male age and reproductive health alongside ovarian function.

The researchers emphasized paternal age as a relevant counseling factor when planning parenthood or fertility treatment because of its possible association with pregnancy maintenance and live birth.

Pregnancy and birth reflect the reproductive health of both partners.

Study source

Juan J. Fraire-Zamora and colleagues at the EUGIN Group, Spain, investigated paternal age, miscarriage and live birth in donor-oocyte IVF. The study was published in Human Reproduction on October 6, 2026. DOI: 10.1093/humrep/deag159.

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