Male Age Affects Female Pregnancy, Male Fertility Drops Worldwide

The number of children needed to be born to each woman to maintain the population level in developed countries is 2.1. Canada's fertility rate in 2010 was 1.63. Annett Vauteck/Photos.com

A new study has found that in addition to the age of women, the age of men also plays a critical role in how successful a female is in getting pregnant.

The Human Reproduction study, published on June 30, looked at how advanced paternal age (APA) impacts live birth rates (LBRs) in IVF/ICSI treatment, two forms of assisted reproductive treatment. It took a retrospective analysis of 18,825 autologous IVF/ICSI cycles. Researchers found that among women under the age of 35 or over 40, the age of the male partner made little difference in their chances of giving birth.

However, among women between the ages of 35 and 40, the study saw a significant drop in the LBR if their male partner was 40 and above. Among 35- to 40-year-old women, the LBR was at 32.8 percent when the paternal age is below 35. This falls to 27.9 percent when paternal age is between 40 and 44, and 25 percent when paternal age is above 55.

“Oocytes in women <35 appear to reduce the negative impact of older sperm on LBR, but not in women 35-39 years of age. This is useful information when counseling couples and in fertility education setting. Further research is needed to clarify the mechanism underlying our findings,” the study said. Oocyte refers to an immature egg.

Speaking to The Guardian, Geeta Nargund, one of four authors who contributed to the study, pointed out that eggs from younger women have the ability to repair greater DNA damage in the sperm of older men. But when women become older, egg quality declines, reducing its ability to make such repairs.

Dropping Male Fertility

A study from 1992 found that sperm counts in men had fallen by 50 percent during the previous 60 years. In another study conducted in 2017, sperm concentration in men between 1973 and 2011 was found to have fallen by 50 to 60 percent worldwide.

In a study conducted in 2019, the proportion of men with normal total motile sperm count was found to have decreased by around 10 percent in the past 16 years.

Scientists have pointed to various factors for the decline in sperm concentration and motile count in men, ranging from air pollution, toxic gasses, heavy metals, pesticides, plasticizers, and so on.

The use of COVID-19 vaccines seems to have added to the problem. A study from Israel has found mRNA COVID-19 vaccines negatively affect male fertility, at least on a temporary basis.

After analyzing 220 samples, researchers found a 15.1 percent reduction in sperm concentration and a 22.1 percent decrease in total motile count 75 to 100 days after vaccination.

The total fertility rate (TFR), expressed as children per woman, has been on a decline in the United States for the past several decades. TFR peaked at 3.582 in 1958 and is at 1.782 in 2022. In Canada, TFR is at 1.492 while the UK has a TFR of 1.753.