The quality of sperm declines with age, so men who plan to delay fatherhood should be counseled to consider sperm banking before age 35, Rutgers University researchers conclude in a new review article.

The paper, published recently in the journal Maturitas, reviewed 40 years of studies of the effects of the father's age on fertility, pregnancy, and the health of children.

"There is evidence that advanced paternal age has significant overall adverse impact," the researchers wrote. "Sperm banking for men who are delaying childbearing may need to be a part of our societal responsibility commencing in the nearby future."

Co-author Gloria Bachmann, an obstetrician-gynecologist who directs the Women's Health Institute at Rutgers' Robert Wood Johnson Medical School, said, "Does it mean doom and gloom? Of course not. What we're talking about are the risks, and they do increase with age."

Last year, she published an article calling for the development of guidelines to advise women about freezing eggs in order to put off motherhood.

Over the last 40 years, both men and women have been having children at later ages on average. In the United States, infants born to older fathers increased from about 4% to 10% during that period, the researchers wrote.

However, experts don't agree on how to define "advanced paternal age." Some studies set the threshold at age 35, others at 45. For women, 35 is a clearer demarcation, because by then, they have only about 3% of the eggs they were born with, and the supply and quality go downhill quickly after that.

While a vast body of research has correlated the mother's age with reproductive outcomes, studies of men are relatively limited.

"Many men," Bachmann and colleagues wrote, "do not think about their age as having any effects on the reproductive process."

The review found much to be concerned about. In an IVF study, the live birth rate fell and miscarriages increased with sperm from men over age 50. Infants born to older fathers were at somewhat higher risk of premature birth, low birth weight and admission to the intensive care unit in some studies. Numerous studies have found children of older fathers are more likely to have a variety of psychiatric disorders, including schizophrenia, autism and obsessive-compulsive disorder.

But some of the research on paternal age is contradictory. For example, two huge population-based studies of pregnancy complications - one looked at one million live births in Ohio and the other looked at 40 million U.S. births - found no increase in preeclampsia, a potentially life-threatening high blood pressure disorder of pregnancy. In contrast, a study of 755,000 births found not only an increase in preeclampsia but also of placental problems.

Whether sperm banking as a hedge against such risks is a good idea, it is rare so far, according to a CNN report. Harry Fisch, a Weill Cornell Medical College urologist and reproductive medicine specialist who wrote a book about the male biological clock, said the increased reproductive risks are "extremely small," so sperm banking - at a storage cost of perhaps $450 a year - "may be excessive."