For women who are older than 35 – or of "advanced maternal age," as designated by the medical community – the risk of miscarriage is clear: the older the woman, the more likely she is to miscarry a pregnancy. The effect of a father's age on miscarriage, on the other hand, is not nearly as defined or as documented, but it does appear to slightly increase the risk. Older fathers cause a slightly increased risk of miscarriage.
Age Matters … Sort Of
A woman's fertility typically begins to decline in her early to mid-thirties, with the sharpest drop occurring around 37 years of age, observes the American Society for Reproductive Medicine. As her fertility begins to decline, a woman's chance of miscarriage begins to climb; by the time a woman is 40, she has a 30 percent chance of miscarriage.
For men, though, age seems to have only a slight impact on fertility, notes Dr. Christine Sanders, an obstetrician and gynecologist with the Hutchinson Clinic in Kansas.
"Fertility declines slightly in older men whose age is greater than 40. Some of this may be due to issues with decreased frequency of intercourse and issues with impotence," she states. "The risk of miscarriage with couples with advanced paternal age increases, but not as much as in women with advanced maternal age."
One study published in the Asian Journal of Andrology found that sudden miscarriages was nearly twice as high in the partners of men who were over the age of 45 versus those who were 25 when they conceived a child, regardless of the woman's age. That study, along with a study published in the Journal of Human Reproduction, also found that when the woman was over 30 years old and the man was over 40, the chance of miscarriage was also significantly increased.
Possible Contributing Factors
In addition to age, other factors may contribute to an increased risk of miscarriage among older fathers, but studies are minimal at best and have focused on professional exposure to toxins, Human Reproduction observes.
Nicotine use also has been shown to increase the risk of miscarriage among older men. Lifestyle concerns, such as excessive stress, participating in competitive sports or extreme exercise, alcohol use and drug abuse, also have been found to increase the risk of miscarriage among men who are older than 35, cites a study in the Pakistan Journal of Medical Sciences, but the results are not statistically significant. "The benefit of diet changes, avoiding tobacco and alcohol are not well known," Sanders says.
Sperm Quality
Although men can father children well into their 80s, that doesn't mean that their sperm or testicular function is of the same quality as a younger man, according to the Human Reproduction study. Men who are between the ages 59 and 74 are more likely to conceive a child with a birth defect, compared to men who are between 23 and 39 years of age.
Moreover, the babies of men who were 50 years of age at the time of conception had a 15 percent higher chance of being born with a birth defect than younger men, according to the Asian Journal study. In addition to miscarriage, these chromosomal abnormalities can lead to common birth defects such as cleft palate, congenital heart disease and congenital hip dislocation, as well as chromosomal disorders like Downs syndrome. Advanced paternal age was also associated with increased risks for esophageal defects, and other musculoskeletal abnormalities.
Genetic Disorders
In addition to birth defects and other chromosomal abnormalities that can occur, advanced paternal age has been associated with a slightly increased risk for at least 10 genetic disorders, according to the Asian Journal study. These include conditions such as:
achondroplasia, a form of dwarfism; craniofacial deformities such as Crouzon syndrome, Apert syndrome and Pfeiffer syndrome; neurological disorders like schizophrenia and bipolar disorder.
Even though the risk of these types of diseases increases with older fathers, the risk is still low, Sanders states. "There is data that shows that there is a small increase in the risk of certain cancers and autism in children born of older fathers," she adds, reiterating that studies are limited.
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