Do you know why delayed fatherhood can cause miscarriage?

Prof. Know Why answers for your general knowledge and awareness on: Do you know why delayed fatherhood can cause miscarriage?

Couples who want to start a family, better plan it early in your life because the more you delay, the stronger becomes the risk of a miscarriage, say the scientists. And this applies to both men and women. Contrary to the older belief that men remain fertile even at old age, this new research points out that delayed fatherhood can also cause miscarriage like late motherhood.

Delayed fatherhood for men is a cause of concern for a healthy pregnancy and the baby as well, doctors warn, after a recent research found that male fertility begins to decline when they reach their mid-30s. Doctors said men who wait until their 40s before starting a family face a greater chance of their partner having a miscarriage, because of the poorer quality of their sperm.

The researchers studied the records of more than 12,000 couples treated for infertility at the fertility clinic, Eylau Centre for Assisted Reproduction in Paris between January 2002 and December 2006; and separated out the influence of male and female ages on the couples' chances of having a baby. They found that women whose partners were 35 or older had more miscarriages than those who were with younger men, regardless of their own age. The men's ages also affected pregnancy rates, which were lower in the over-40s.

The study looked at pregnancies and miscarriages recorded for couples having IUI treatment at the clinic. It found the risk of miscarriage was on average 16.7% when men were aged 30-34. That rate rose to 19.5% when men were 35-39 and 33% in men aged 40 or over.

The findings are a concern, researchers say, because of the trend for men to delay fatherhood. Stéphanie Belloc, lead author of the study, said that until now, gynecologists only focused on maternal age, and the message was to get pregnant before the age of 35 or 38 because afterwards it would be difficult. But now the gynecologists must also focus on paternal age and give this information to the couple.

Yves Ménézo, an embryologist at the Eylau Centre for Assisted Reproduction, said older men become less fertile because genetic defects build up in their sperm. In younger men, the damage is minor and can be repaired inside the fertilized egg. But in older men the amount of DNA damage can overwhelm the body's natural repair mechanisms. "We think there's a critical threshold of DNA damage and above that, the damage can no longer be repaired. When that happens, genetic mistakes get through to the embryo and you get an increase in miscarriages," Ménézo said.

Jacques de Mouzon, a co-author at the French National Institute for Medical Research, said: "People say men are fertile into old age, 90 even. That may be true sometimes, but the product is different and there are more semen abnormalities as age advances. There is a decrease [in male fertility] and an increase in the spontaneous abortion rate after the age of 40 and especially after 45. It is necessary for men to try to have children before the ages of 40 to 45."

Previous research has pointed to a slight increase in birth defects in babies born to older men. A 2005 study of 70,000 couples by epidemiologist Jorn Olsen at the University of California, Los Angeles, found a fourfold rise in Down's syndrome among babies born to men aged 50 and older. They were also more likely to have limb deformities.

Dr Allan Pacey, a fertility expert at Sheffield University and secretary of the British Fertility Society, said: "There is growing evidence from a number of studies to show that men are not totally immune from reproductive ageing. "Previous studies of couples trying to conceive naturally or undergoing IVF have shown that men over the age of about 40 are less fertile than younger men. Moreover, if they do achieve a pregnancy their partners are more likely to miscarry. This study reinforces the message that men aren't excused from reproductive ageing."

Normally, men don't typically worry about reproductive ageing, but perhaps they should if the study is to be believed, as now, delayed fatherhood is also being linked to miscarriages, and birth deformities.

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