More on Men's Fertility Decline with Age

The Irish Times reports that the chances of miscarriage increases with the man's age.

A new study presented last week at the annual meeting of the European Society of Human Reproduction and Embryology in Barcelona found that miscarriage rates increased significantly when the man was older than 35, and that pregnancy rates dropped when the man was older than 40. The study was based on more than 12,000 couples attending a fertility clinic in Paris....

Prof Sheena Lewis, who is a scientist at the Regional Fertility Centre at the Royal Victoria Hospital in Belfast, said there was a growing trend of people leaving it later to have children when their careers were established, and of people trying to start second families later in life. She said the clinic was seeing an increasing number of men in their 40s and 50s who wanted to have children, often in a second relationship....

She said there were now quite a number of studies showing that as a man ages, the likelihood of his sperm being damaged increases. "A sperm is a very specialised little cell - it is just DNA with a tail and it has one single function, to get the DNA to the egg to fertilise it. In order to do that, the cell gets rid of everything but DNA, so it gets rid of repair mechanisms that you find in other cells. So if it gets damaged it can't repair itself."

She said that after fertilisation, the DNA damage of the sperm becomes part of the genetic make-up of the embryo. "If a poor sperm fertilises an egg, and even if you get a pregnancy, there is quite often a miscarriage," Prof Lewis said.

Read the whole article.

Older fathers

Regular readers of this blog are already aware that research is beginning to show elevated risks of genetic defects for children of older fathers. Here is another report on this subject.

A mass study found that deaths of children fathered by over-45s occurred at almost twice the rate of those fathered by men aged between 25 and 30.

Scientists believe that children of older fathers are more likely to suffer particular congenital defects as well as autism, schizophrenia and epilepsy. The study was the first of its kind of such magnitude in the West, and researchers believe the findings are linked to the declining quality of sperm as men age.

A total of 100,000 children born between 1980 and 1996 were examined, of whom 830 have so far died before they reached 18, the majority when they were less than a year old. ...
The deaths of many of the children of the older fathers were related to congenital defects such as problems of the heart and spine, which increase the risk of infant mortality. But there were also higher rates of accidental death, which the researchers believe might be explained by the increased likelihood of suffering from autism, epilepsy or schizophrenia....
Previous research using the same data found that older men were four times as likely to father a child with Down's syndrome, while other studies have found that the genetic quality of sperm deteriorates as men age.

Further unintended consequences of our Brave New World of separating sex from reproduction and postponing child-bearing.

Male Biological Clock

We are all familiar with teh fact that women's fertility declines with age. We are now discovering that male fertility does as well. And worse, the damage to male sperm may do more than reduce the likelihood of conception. Advanced paternal age has been implicated in a number of birth defects. From an article in Psychology Today:

Nonetheless, a virtual tidal wave of recent research has made it irrefutable: Not only does male fertility decrease decade by decade, especially after age 35, but aging sperm can be a significant and sometimes the only cause of severe health and developmental problems in offspring, including autism, schizophrenia, and cancer. The older the father, the higher the risk. But what's truly noteworthy is not that infertility increases with age—to some degree, we've known that all along—but rather that older men who can still conceive may have such damaged sperm that they put their offspring at risk for many types of disorders and disabilities.

The mechanism seems to be that as men age, their DNA does not replicate as accurately as at earlier ages. Therefore, small abnormalities in the genetic struction which are not large enough to be fatal, can cause a wide array of damage to the child:

These mutations could reflect the differences in male and female reproduction, notes Jabs (Ethylin Wang Jabs, professor of pediatric genetics at Johns Hopkins University). By the time females reach their teen years, their eggs have already been formed—just one new egg matures each month. Men, on the other hand, produce millions of sperm cells every time they ejaculate. After each ejaculation, they must literally replicate those cells, and each replication multiplies the chance for a DNA "copy error"—a genetic chink in the sperm DNA. The more ejaculations a man produces, the greater the chance for chinks to arise, leading to increased point mutation and thus increased infertility and birth defects. While a woman's reproductive capacity halts more or less abruptly after all her eggs have been used up somewhere in their forties or fifties, men experience a longer, more gradual winnowing and disintegration. "We believe that something in men's DNA replication machinery keeps becoming less efficient and less accurate with age, and the problems accumulate," says Jabs.

This is yet another unintended consequence of delaying childbirth, a delay made possible by conctraception. We are increasingly organizing society around the premise that sex is essentially a sterile activity, with childbearing thrown in as an after-thought, if you happen to like that sort of thing. Widespread access to contraception has made indefinite postponement of childbearing the norm, not the exception among the educated classes.
It is time to rethink this.

Taxpayers Left Holding the Baby

Taxpayers Left Holding the Baby is the name the Oklahoma Council of Public Affairs gave to my article about the fact that 55% of births in that state were paid for by Medicaid. I don't cite the usual cuplrits. The young women of Oklahoma are not stupid. But the older people who make policy may be....

A Possible Explanation for Infertility: donuts?

I don't know how seriously to take this story from the UK. The article reports on findings that an increased consumption of transfats may be correlated with impaired fertility. It is possibly true, since it is certainly conceivable that diet plays a role in ovulation. Or, it could be that people would prefer to blame the Villain of the Month, namely transfats, rather than focus on the delayed age at first marriage and subsequent older age at first pregnancy attempt as the primary causes of infertility.

In the study, researchers from the Harvard School of Public Health in Boston looked at 18,500 women trying to conceive and found 438 cases of ovulatory problems.
If a woman does not ovulate there is no egg for sperm to fertilise and so she cannot become pregnant. The scientists found that those who took two per cent of their energy intake from trans fats, instead of carbohydrates or polyunsaturated fats such as sunflower oil, had a 70 per cent greater risk of infertility through lack of ovulation. Those whose energy came from trans fats instead of monounsaturated fats such as olive oil were twice as likely to have problems. The amount of trans fats needed to reach the two per cent levels was just four grams a day in a 2,000-calorie diet. People could easily eat that much in a meal of pie and chips or just one doughnut.

I'll be watching for more details on this intriguing study.