Male Age May Affect Miscarriage Rate

It is no surprise that Dr. Belloc’s claim has received much attention from the media. Her findings, which she was to announce to the European Society of Human Reproduction and Embryology on July 7, 2008, are supposed to have demonstrated an increase in the miscarriage rates when the father was over the age of 35. The group of researchers conducted the study between January 2002 and December 2006. It included over 21,000 artificial inseminations of over 12,000 couples, most of who were being treated for male infertility. Dr. Belloc and associates of the Eylau Centre for Assisted Reproduction in Paris, France measured the sperm quality and recorded rates of clinical pregnancy (pregnancy verified by ultrasound), miscarriage and delivery. The researchers claim that they were able to divide the variables in their in-depth analysis of the results.

According to the study, miscarriage rates increased in relation to paternal age. The miscarriage rates were

• Nearly 17 percent if the father was over 34 years old
• Around 20 percent if the father was between the ages of 35 and 39
• Over 32 percent if the father was older than 44

Previous Research Suggests a Link between Paternal Age and Infertility

It is not news that paternal age could play a factor in infertility, another proposed finding in Dr. Belloc‘s study. Many other scientists have conducted studies to compare the semen quality of younger men to older men. Such studies have tested the semen for volume, concentration, motility (how well the sperm move) and morphology (the structure of the sperm). In February of 2001, S. A. Kidd , B. Eskenazi and A.J. Wyrobek conducted an analysis of almost 20 years of research from 1980 to 1999. When they compared thirty-year-old men to fifty-year-old men, the semen quality was impaired by

• Volume by 3-22%
• Motility by 3-37%
• Morphology 4-18%

The researchers noted that there did not seem to be any relation to male age and sperm concentration.

Though there is a variation in the statistics, the findings have led many fertility specialists to assume a link between paternal age and infertility. However, the evidence for a link between advanced male age and increased miscarriage rates, up to this point, has been relatively obscure.

Maternal Factors Related to Miscarriage

Miscarriage research is hard to come by, considering the extreme difficulty in controlling the vast number of variables that play a factor in pregnancy loss. There are a few causes, however, on which many specialists agree, including female structural abnormalities, hormonal imbalances, blood disorders and age. Researchers have linked maternal age to an increase in miscarriage and in chromosomal abnormalities, such as trisomy 21 (Down’s syndrome). However, many specialists have assumed that paternal age is not an important factor due to the process of selection.

The Process of Sperm Selection Seems to Rule Out Male Causes of Miscarriage

Males produce sperm in vast quantities, and these sperm face rigorous challenges in reaching their destination, the female egg. Under normal circumstances, they must go through the harsh environment of the vagina, find their way through the cervix and into the uterus, and choose the one of two fallopian tubes that leads to the egg. Because of the difficulty of the process, it seems that only a healthy sperm would be the one of millions to win the contest. Thus, once pregnancy is established, it would make sense that the male portion would not be defective. Dr. Belloc’s study would have us rethink this assumption.

Dr. Belloc and her colleagues have not yet released their actual research document to the public. Further examination of the data is essential before any conclusions can be set. Additionally, scientists will need to duplicate it many times, yielding similar results, in order to prove its efficacy.

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