Testosterone levels are a key factor in a family's health and happiness after a newborn arrives. Researchers have found that a drop can signal postpartum depression in dad, and a spike may be a sign of aggression.
Postpartum depression is often associated with mothers, but a new study shows that fathers face a higher risk of experiencing it themselves if their testosterone levels drop nine months after their children are born.
The same study revealed that a father's low testosterone may also affect his partner -- but in an unexpectedly positive way. Women whose partners had lower levels of testosterone postpartum reported fewer symptoms of depression themselves nine and 15 months after birth.
High testosterone levels had the opposite effect. Fathers whose levels spiked faced a greater risk of experiencing stress due to parenting and a greater risk of acting hostile- such as showing emotional, verbal or physical aggression -- toward their partners.
The study was published in the journal Hormones and Behavior on Sept. 1. The findings support prior studies that show men have biological responses to fatherhood, said Darby Saxbe, the study's lead author and an assistant professor of psychology at USC Dornsife College of Letters, Arts and Sciences.
"We often think of motherhood as biologically driven because many mothers have biological connections to their babies through breastfeeding and pregnancy." Saxbe said. "We don't usually think of fatherhood in the same biological terms. We are still figuring out the biology of what makes dads tick.
"We know that fathers contribute a lot to child-rearing and that on the whole, kids do better if they are raised in households with a father present," she added. "So, it is important to figure out how to support fathers and what factors explain why some fathers are very involved in raising their children while some are absent."
Saxbe worked with a team of researchers from USC, University of California at Los Angeles and Northwestern University.
A snapshot of paternal postpartum depression
For the study, the researchers examined data from 149 couples in the Community Child Health Research Network. The study by the National Institute for Child Health and Human Development involves sites across the country, but the data for this study came from Lake County, Illinois, north of Chicago.
Mothers in the study were 18 to 40 years old; African-American, white or Latina; and low-income. They were recruited when they gave birth to their first, second or third child. Mothers could invite the baby's father to participate in the study as well. Of the fathers who participated and provided testosterone data, 95 percent were living with the mothers.