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Daddy's influence? The surprising connection between fathers and their offspring during pregnancy

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Popular convention may dictate that the father’s role in the early development of his children pales in comparison to the mother’s, but author Paul Raeburn is shedding new light on the science behind the vital role of the often overlooked male parent. Please consider for your afternoon plans.  

In 2010, Prakesh S. Shah of the University of Toronto noted that scant research had been done on whether there was any link between fathers and either preterm infants or those born full-term with low birth weight. (Both outcomes increase the risk of illness or death in the first days and weeks of life.)

Most research had been done on mothers, as you might expect, where the possibility of a link between the mother’s adverse health or behavior and her infant’s outcome might be easier to understand. Mothers’ risk factors for adverse outcomes have been studied extensively, for the obvious reason that mothers contribute far more to their children during the nine months of gestation than fathers do. That’s a fact of biology.

But that doesn’t mean fathers should be overlooked. To remedy the lack of information on fathers, Shah and his colleagues collected thirty-six studies and analyzed them to see what links they might reveal between fathers and birth outcomes. They concluded that these adverse outcomes in babies were more likely to occur as fathers grew older and if the fathers had been born with low birth weight themselves.    

The Toronto study was accompanied by a commentary in the same issue of the American Journal of Obstetrics and Gynecology, in which another group of researchers criticized the team for not going further.

The critics said the scientists had failed to consider a long list of paternal factors that could influence birth outcomes. These include how fathers feel about the pregnancy, their behavior during the pregnancy, and their relationships with the mothers.

All of these circumstances can increase mothers’ stress during their pregnancies and affect how well they take care of themselves. When fathers don’t want to have the baby, mothers are less likely to get prenatal care. Cigarette smoking by fathers can influence a mother’s decisions regarding smoking and increase the likelihood of low birth weight.

The commentary marked a rare instance of researchers being publicly criticized for failing to give fathers greater consideration in research. It ended with a recommendation that doctors and scientists devote more attention to fathers when assessing pregnancy risks. It’s a good sign: attitudes are changing.

An example of the kind of research the critics were advocating has come out of a group at the University of South Florida led by Amina Alio, a professor of community and public health. She and her colleagues found that fathers who were involved with their partners during pregnancy reduced the risk that the children would die in the first year of life.

Infants whose fathers were absent— and had no involvement in the pregnancy— were more likely to be born with lower birth weight and to be born prematurely. The death rate of infants whose fathers were not around was nearly four times that of infants whose fathers were involved.

And many maternal complications that could affect the infants— such as anemia, high blood pressure, and more serious ailments— were more prevalent among women whose children’s fathers were absent.

Yet another study out of New Zealand in 2011 looked at how fathers could affect the birth weight of their children. The group recruited 2,002 couples while the women were pregnant and followed them until birth.

Was there a connection, they wondered, between obesity or blood pressure in fathers and the size of their children? Nothing appeared to link blood pressure to birth weight, but something quite startling appeared when they looked at fathers’ weight: obesity in fathers, and what’s called central obesity, or abdominal fat, were each associated with a 60 percent increase in the risk of having a child with a low birth weight. It didn’t matter whether the mother was obese.

This was a revelation. Once fathers have fertilized an egg, they have no physiological connection with their developing fetuses. But somehow they are affecting the children’s physiology. How does this happen? One guess is that mothers and fathers tend to eat similar diets, and so a father’s overeating could influence his partner. Another is that somehow the father’s genes are influencing the baby’s growth in utero— exactly how that might happen is not known.

These discoveries posed yet another challenge to the exclusive research focus on mothers. No one had seen the importance of fathers during pregnancy because investigators had never looked for it.

Excerpted from Do Fathers Matter? What Science Is Telling Us About the Parent We’ve Overlooked, by Paul Raeburn (Scientific American/FSG, 2014).

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