Women have long understood that general fitness and age are both critical to conceiving a healthy child. But their partners often feel absolved of such concerns; men tend to think they can drink, carouse, smoke like coal trains, and conceive whenever they want, with no impact on fertility or their future offspring. Would that it were so.
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.
In the past several years, studies worldwide have found that with each passing decade of their lives and with each insult they inflict on their bodies, men's fertility decreases, while genetic risk to offspring slowly mounts. The range of findings is staggering: Several studies have shown that the older the man, the more fragmented the DNA in his ejaculated sperm, resulting in greater risk for infertility, miscarriage or birth defects.
Male vs. female mutations
Scientists have long known that advanced paternal age (like increased maternal age) played some role in fertility problems and birth defects. Yet because the reports mainly involved children who died before birth or who had extremely rare disorders, no one really rang the alarm. Now, with new studies linking the father's age to relatively frequent, serious conditions like autism, schizophrenia, and Down syndrome, the landscape is shifting.
Women have unfairly borne the brunt of the blame for birth defects. When the conditions were familial, passed on through chromosomal lineage, women were somehow widely believed culpable, even though such defects can be traced to either partner.
A chilling finding
The biggest news -- the father's role in brain disorders -- has come to light largely because of research from Israel, where birth records routinely include the age of the male parent. The first unsettling finding linked paternal age and schizophrenia.
"In our first study, looking at every pregnancy in Jerusalem from 1964 to 1976, we found that increased age in the father predicted increased cases of schizophrenia in the children," explains Malaspina, who was on the team doing the work. "In our second study we found that when the cases arose from new mutations--not familial inheritance--it almost always could be traced to the genetics of the father. Somewhere between a quarter and a third of the cases could be explained only by the age of the father--a threefold risk linked to fathers older than 50 compared with those in their 20s." Studies in Sweden and California produced almost identical results.
The autism findings are even more disturbing: Men 40 and older in the Israeli study were almost six times as likely to have offspring with autism than men under 30. Some researchers believe that older fathers may hold a clue to the vast upsurge in autism cases in the past decade. "With older and older couples having children--in the past two years, for the first time, more babies are being born to women over age 30 than under age 30, and on average, male partners tend to be older than female partners--it's very feasible that paternal age is a major predictor of autism," asserts Fisch.
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.
In the past several years, studies worldwide have found that with each passing decade of their lives and with each insult they inflict on their bodies, men's fertility decreases, while genetic risk to offspring slowly mounts. The range of findings is staggering: Several studies have shown that the older the man, the more fragmented the DNA in his ejaculated sperm, resulting in greater risk for infertility, miscarriage or birth defects.
Male vs. female mutations
Scientists have long known that advanced paternal age (like increased maternal age) played some role in fertility problems and birth defects. Yet because the reports mainly involved children who died before birth or who had extremely rare disorders, no one really rang the alarm. Now, with new studies linking the father's age to relatively frequent, serious conditions like autism, schizophrenia, and Down syndrome, the landscape is shifting.
Women have unfairly borne the brunt of the blame for birth defects. When the conditions were familial, passed on through chromosomal lineage, women were somehow widely believed culpable, even though such defects can be traced to either partner.
A chilling finding
The biggest news -- the father's role in brain disorders -- has come to light largely because of research from Israel, where birth records routinely include the age of the male parent. The first unsettling finding linked paternal age and schizophrenia.
"In our first study, looking at every pregnancy in Jerusalem from 1964 to 1976, we found that increased age in the father predicted increased cases of schizophrenia in the children," explains Malaspina, who was on the team doing the work. "In our second study we found that when the cases arose from new mutations--not familial inheritance--it almost always could be traced to the genetics of the father. Somewhere between a quarter and a third of the cases could be explained only by the age of the father--a threefold risk linked to fathers older than 50 compared with those in their 20s." Studies in Sweden and California produced almost identical results.
The autism findings are even more disturbing: Men 40 and older in the Israeli study were almost six times as likely to have offspring with autism than men under 30. Some researchers believe that older fathers may hold a clue to the vast upsurge in autism cases in the past decade. "With older and older couples having children--in the past two years, for the first time, more babies are being born to women over age 30 than under age 30, and on average, male partners tend to be older than female partners--it's very feasible that paternal age is a major predictor of autism," asserts Fisch.
