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 That a male's preconception behaviors and exposure to all sorts of environmental contaminants (alcohol, drugs, medicines, chemicals at work, pesticides, etc) has effects on sperm and is linked to birth defects has been known for decades. What is new is the focus on epigenetics, or as some researchers call it: inherited paternal epigenetics. Three different paternal influences that affect the fetus and child (thus paternal experiences influence what the child inherits) are discussed in a review article: paternal age, environmental factors, and alcohol consumption.The researchers also found that environmental effects during the lifetime of a father can affect not only his immediate offspring, but also future generations.

What is epigenetics? Researchers in the study summarized it as: "Epigenetics are heritable alterations in gene expression that do not involve changes in the germline DNA sequence. It works primarily through three mechanisms: DNA methylation, histone modification, and microRNA (miRNA) expression."

Huh? This means that in epigenetics, the DNA doesn't change, but external or environmental factors switch genes on and off and affect how cells read genes. In other words, it's how the environment can alter gene expression without changing the genetic code. Epigenetic change is a regular and natural occurrence, but can also be influenced by several factors: age, the environment/lifestyle (such as diet, alcohol consumption, and chemical exposure), and disease state.  For example, what you eat and how much you drink (alcohol), where you live, what chemicals you're exposed to, how you exercise, even aging – all of these can eventually cause chemical modifications around the genes that will turn those genes on or off over time. Additionally, in certain diseases such as cancer or Alzheimer’s, various genes will be switched into the opposite state, away from the normal/healthy state. From Science Daily:

Fathers' age, lifestyle associated with birth defects

A growing body of research is revealing associations between birth defects and a father's age, alcohol use and environmental factors, say researchers at Georgetown University Medical Center. They say these defects result from epigenetic alterations that can potentially affect multiple generations. The study, published in the American Journal of Stem Cells, suggest both parents contribute to the health status of their offspring -- a common sense conclusion which science is only now beginning to demonstrate, says the study's senior investigator, Joanna Kitlinska, PhD, an associate professor in biochemistry, and molecular and cellular biology.

"We know the nutritional, hormonal and psychological environment provided by the mother permanently alters organ structure, cellular response and gene expression in her offspring," she says. "But our study shows the same thing to be true with fathers -- his lifestyle, and how old he is, can be reflected in molecules that control gene function," she says. "In this way, a father can affect not only his immediate offspring, but future generations as well."

For example, a newborn can be diagnosed with fetal alcohol spectrum disorder (FASD), even though the mother has never consumed alcohol, Kitlinska says. "Up to 75 percent of children with FASD have biological fathers who are alcoholics, suggesting that preconceptual paternal alcohol consumption negatively impacts their offspring."

The report is a review of evidence, human and animal, published to date on the link between fathers and heritable epigenetic programming. Among the studies reviewed are ones that find: - Advanced age of a father is correlated with elevated rates of schizophrenia, autism, and birth defects in his children; - A limited diet during a father's pre-adolescence has been linked to reduced risk of cardiovascular death in his children and grandchildren; - Paternal obesity is linked to enlarged fat cells, changes in metabolic regulation, diabetes, obesity and development of brain cancer; - Psychosocial stress on the father is linked to defective behavioral traits in his offspring; and - Paternal alcohol use leads to decreased newborn birth weight, marked reduction in overall brain size and impaired cognitive function.

 This is an issue that a lot of women I've known over the years have wondered about: if a woman gets pregnant while on birth control pills (oral contraceptives) - and many women do - does it mean higher rates of birth defects? This study says NO to higher rates of major birth defects which is very reassuring, but it doesn't answer the issue of more subtle effects (e.g., behavioral effects) from the hormones in the contraceptives. From Medical Xpress:

Oral contraceptive use not associated with increased birth defects risk

Oral contraceptives taken just before or during pregnancy do not increase the risk of birth defects, according to a new study by researchers from Harvard T.H. Chan School of Public Health and the Statens Serum Institut in Denmark. They found that the prevalence of major birth defects was consistent (about 25 per 1,000 live births) across all pregnant women in the study population regardless of contraceptive use.

Even though oral contraceptives are more than 99% effective with perfect use, almost 10% of women become pregnant within their first year of use. Many more women will stop using oral contraceptives when planning a pregnancy and conceive within a few months. Little is known about the potential health effects to children from in utero exposure to the hormones in oral contraceptives.

....Charlton and colleagues were able to tap into a wealth of data collected from multiple Danish health registries between 1997 and 2011 and linked by the unique personal identification number assigned to all Denmark residents. The researchers looked at 880,694 live-born infants, and the health of these children at one-year follow-up. Oral contraceptive use was estimated based on the date of the mother's most recently filled prescription.  Among the women in the study population, a fifth had never used oral contraceptives before becoming pregnant, and more than two-thirds had stopped using oral contraceptives at least three months before becoming pregnant. Eight percent had discontinued use within three months of becoming pregnant, and 1%, or well over 10,000 women, had used oral contraceptives after becoming pregnant.

The prevalence of birth defects was consistent across each category of oral contraceptive use, and remained so when the researchers added in pregnancies that ended as stillbirths or induced abortions.

There has been much discussion lately on declining male sperm counts and what it means. From Medical Xpress:

No link found between low sperm count, birth defects

Having a low sperm count doesn't seem to determine whether a man's children will be born with birth defects, a new study indicates.

With infertile couples, men are partially or fully responsible for the inability to conceive about 40 percent of the time. Assisted reproductive technologies such as in vitro fertilization can help couples have children, but research has suggested a possible link between these approaches—when used to treat infertility problems in the male partner—and a higher risk of birth defects.

In the new study, researchers examined a Baylor College of Medicine database in search of possible connections between birth defects and low sperm count. The researchers didn't find any links.

But the following finding is a cause for concern. From Science Daily:

Male infertility linked to mortality, study shows

Men who are infertile because of defects in their semen appear to be at increased risk of dying sooner than men with normal semen, according to a study. Men with two or more abnormalities in their semen were more than twice as likely to die over a roughly eight-year period as men who had normal semen, the study found.