We all know that after a certain age, women can no longer get pregnant, while men can father children well into old age. New research by scientists at Rutgers University suggests, however, that men should also have their children before they get too old, to minimize the risk to the health of their children as well as their partners. The work assessed various studies like this one on the impact of parental age on children's health, pregnancy, and fertility, which were performed over forty years. The findings have been reported in Maturitas.
"While it is widely accepted that physiological changes that occur in women after 35 can affect conception, pregnancy and the health of the child, most men do not realize their advanced age can have a similar impact," noted study author Gloria Bachmann, director of the Women's Health Institute at Rutgers Robert Wood Johnson Medical School.
There is not a standard that defines advanced parental age in men; it can range from age 35 to 45. The number of American infants born to dads over 40 has risen to about ten percent of live births over the past four decades. There may be several reasons for this shift, including advances in fertility treatments and lifestyle choices.
This research indicated that fertility decreases in men over the age of 45. There is an increase in the risk of complications during pregnancy for their partners, such as preeclampsia, preterm birth, and gestational diabetes. The infants have an increased incidence of health problems as well; the chances of late stillbirth, premature birth, low birth weight, seizures, and some congenital defects like heart disease are all higher. Their health issues can continue as the infants get older as well. Children of fathers over 45 are more likely to have autism, childhood cancer, cognitive and psychiatric disorders.
Bachmann hypothesized that these effects are related to the natural decrease in testosterone that happens as men get older, in addition to poor quality semen and degraded sperm. More research has to be done, however, to fully understand the causes.
"In addition to advancing paternal age being associated with an increased risk of male infertility, there appears to be other adverse changes that may occur to the sperm with aging. For example, just as people lose muscle strength, flexibility, and endurance with age, in men, sperm also tends to lose 'fitness' over the life cycle," she said.
As men age, the stress on their body can negatively impact sperm, lowering the number and changing it in a way that alters the zygote, and incorporates into the DNA of the offspring.
"In addition to decreasing fertilization potential, this can also influence the pregnancy itself, as is noted by increased pregnancy risks when conception is successful," she added.
The video above explores the benefits and risks of putting off fatherhood until late in life.
The genetic mutations that can occur may also contribute to the development of diseases later in life.
"Although it is well documented that children of older fathers are more likely to be diagnosed with schizophrenia -- one in 141 infants with fathers under 25 versus one in 47 with fathers over 50 -- the reason is not well understood," she said. "Also, some studies have shown that the risk of autism starts to increase when the father is 30, plateaus after 40 and then increases again at 50."
Older men can have fertility problems even when their partner is under 25.
"While women tend to be more aware and educated than men about their reproductive health, most men do not consult with physicians unless they have a medical or fertility issue," Bachmann added.
Bachmann recommended that older men who are planning on having children late in life should bank their sperm before they are older than 35, and they should get counseling from their physician to minimize risks.