Does age affect fertility

The biological clock is ticking How fertility decreases with age

A baby aged 35 and over? This is generally less likely than it is for younger women. But new studies show amazing things about fertility in old age. The most important facts and the ending of Myth 35.

A woman is not fertile all her life. Rather, the length of fertility is determined before birth. The female embryo has around two million egg cells. At the start of the first period there are still around 400,000. “The egg cells begin to mature after puberty. At some point they will be used up, ”says Dr. Mathias Brunbauer, head of the fertility clinic Vienna.

Declining fertility from the age of 35 has long been cited. The probability of pregnancy is therefore only 10 percent, for 40-year-olds even only five percent. Many women are familiar with this fact and it may even be a trigger for “baby panic” from the end of their twenties. But the rigid age limits of 30, 35, 40 years have hardly been statistically proven.

Studies on the decrease in fertility in women

It is controversial when and how much female fertility decreases. The rigid age information that one in three 35- to 40-year-olds will not become pregnant within a year was originally published in 2004 in the science journal “Human Reproduction”. However, the database of the numbers is out of date and is based on French birth records between 1670 and 1830.

Two other publications, “Management of the infertile women” by Helen A. Carcio and “The Fertility Sourcebook” by M. Sara Rosenthal, have now been criticized by science. The linear decline in female fertility from the age of 18 years onwards is not proven.

the essentials in brief

  • The fertility of men and women decreases with age
  • The fertility curve does not fall linearly from the age of 18
  • New studies show: The negative effect of biological age has been greatly overestimated
  • People over the age of 35 can naturally also become pregnant

New studies come to a different conclusion: In 2004 David Dunson published a study in the journal “Obstetrics & Gynecology”. The data from 770 contemporary European women showed that the fertility of women in their mid-thirties and late twenties differed by only four percentage points if they had sex twice a week for a year.

This result was also confirmed by Anne Steiner, assistant professor at the North Carolina School of Medicine. On the basis of the numbers available to her, she too could not determine a large decrease in fertility before the woman's forty years of age. These refer to women who become pregnant for the first time. For women who have already been through pregnancies, it is generally easier to get pregnant again.

At Bosten University, researchers examined 2,820 Danish women during the period in which they were trying to conceive. Among those who had sex during their fertile days, 78 percent of 35 to 40 year olds became pregnant within a year. There were hardly any more among the 20 to 34-year-olds: 84 percent.

The current conclusion of science: The negative effect of biological age has so far been greatly overestimated.

The most fertile years of women

Although the chances of getting pregnant at 40 are not bad, biologically speaking, of course, the earlier the better. The younger the woman, the more regular the cycle and the healthier the egg cells.

But there are many reasons why women in Western societies are becoming more and more late to mothers. The apprenticeship, the start of the job and the career take several years. In addition to professional experience and some savings on their account, many women also want a stable relationship.

In Switzerland the trend is clear. The mothers are getting older. In 1975, the average age of first-time mothers in Switzerland was 27; today women are on average 31.5 years old when they become a mother for the first time.

Fertility from 35 years

Despite the widespread assumption that the desire to have children is over at the age of 35, according to current studies there is no reason for a “shot panic”. Fertility decreases, but the vast majority of women over 35 get pregnant naturally.

Also Read: These 8 Tips To Help You Get Pregnant Over 30

However, there are some limitations. For example, older women no longer ovulate each cycle and egg cells are damaged more often, increasing the risk of miscarriage or chromosomal damage to the embryo.

From a purely statistical point of view, other fertility-related risks also increase after the age of 35. Gestational diabetes, high blood pressure and the risk of a placenta lying in front of the cervix, a so-called placenta previa, occur more often than in very young women. All of these factors contribute to the fact that women aged 35 and over are considered to be “high-risk pregnancies”.

Get pregnant when you are over 40 years of age

More and more women in Switzerland are having babies over the age of 34, including women aged 40 and over. Pregnancy at the age of 40 and later is biologically entirely possible, although it is statistically more difficult and can take longer. But there are often couples who, despite medically confirmed poor conditions, get pregnant quickly, while others with good prognoses do not want to work. And should it not work, the reproductive medicine of the fertility centers offers a wide range of help.

How male fertility changes with age

Not only do women have their children later and later, men are also having older and older fathers. According to the Swiss Federal Statistical Office, the majority of live births have fathers between 30 and 39 years old. Every fifth father is 40 years of age or older.

Just as the quality of egg cells and the frequency of ovulation decrease with age in women, the quality of sperm also decreases in men around 40 years of age. If the desire to have children is underfilled, a spermiogram is therefore also carried out in men, in which the sperm and seminal fluid are analyzed. Damaged cells can cause chromosomal damage in the embryo or even miscarriages.

However, the fertility of both sexes is not only determined by biological age. Smoking, obesity and plastic residues in food and the environment can also reduce the quality of egg cells and sperm.

It was not until 2017 that scientists published in the journal "Human Reproductive Update" that between 1973 and 2011 the number of sperm cells per milliliter of sperm in men from Western countries had fallen by 52.4 percent. For reassurance: It is not only the number of sperm cells, but also their quality and mobility that are decisive for the fertilization of the egg cell.