THURSDAY, Feb. 7 (HealthDay News) -- In a finding that seems to turn conventional wisdom on its head, researchers report that babies of teenage fathers are more likely to be born with health problems than babies born to men over 40.
"We found that being a teenage father was associated with an increased risk of adverse pregnancy outcomes, including preterm birth, low birth weight and neonatal deaths," said Dr. Shi Wu Wen, an associate professor at the University of Ottawa Department of Epidemiology & Community Medicine.
In the study, Wen's team used data from the National Center for Health Statistics to collect information on 2,614,966 births in the United States between 1995 and 2000. To isolate the effects of the teen fathers' age on the outcome of pregnancy, the researchers compensated for the mother's contribution by choosing women 20 to 29 years old.
Women in this age group are less likely to be affected by fertility problems, which can have an effect on birth outcomes, Wen noted. "We also excluded infants with birth defects," he said. "This may explain why we didn't see adverse effects amongst older fathers."
The researchers found that babies born to teenage fathers had a 15 percent increased risk of premature birth, a 13 percent increased risk for low birth weight, and a 17 percent increased risk for being small for gestational age.
These babies also had a 22 percent increased risk of dying within the first month after birth, and a 41 percent increased risk of dying in the first four weeks to one year after birth, although the absolute risk was small -- less than 0.5 percent, the researchers said.
Babies of fathers 40 and older did not experience the same risks, Wen said.
"The public has paid attention to teenage pregnancy, but mostly to teenage mothers," Wen said. "But here we show that teenage fathers are also at high risk. The public and health agencies should pay attention to teenage fathers."
The findings are reported in the February issue of Human Reproduction.
Wen said it's not clear why infants of teenage fathers are at greater risk for health problems. However, he suspects that social factors such as income and lifestyle play a role.
"Young fathers have less stable employment," Wen said. "In addition, teenagers are at risk for more risky behavior like smoking and alcohol and drug use. These are known to be associated with adverse pregnancy outcomes.
"Teenage fathers may also be emotionally less stable," he added. "We know that stress is a risk factor for adverse pregnancy outcomes as well."
One expert agrees that more attention should be paid to teenage fathers and their contribution to the health of their children.
"Paternal age is an ignored and understudied and underestimated contributor to neonatal outcomes," said Dr. F. Sessions Cole, director of newborn medicine and head of the neonatal intensive care unit at St. Louis Children's Hospital. "It's 50 percent egg and 50 percent sperm that form the baby, and 100 percent of the blame is attributed to mothers," he said.
"The risk-taking behaviors of adolescent males probably are a significant part of the reason why their sperm are associated with more adverse neonatal outcomes," Cole said. "These risk-taking behaviors impact sperm in ways we don't know."
Cole believes teenage fathers, like teenage mothers, should receive prenatal counseling. "That way, a prospective father can get some sense of what he can do to optimize the outcome," he said.
For more on healthy babies, visit the U.S. Food and Drug Administration.
SOURCES: Shi Wu Wen, M.D., Ph.D., associate professor, Department of Epidemiology & Community Medicine, University of Ottawa, Canada; F. Sessions Cole, M.D., director, newborn medicine, and head, neonatal intensive care unit, St. Louis Children's Hospital; February 2008 Human Reproduction