It is well known that testosterone is the primary hormone that increases bone and muscle mass as males grow. But could the very thing that strengthens boys during adolescence also be responsible for weakening them during infancy?
That is one of the possibilities being examined by June Cho, PhD, an Assistant Professor in the UAB School of Nursing, who has been awarded a five-year, $1.72 million R01 grant from the National Institute of Child Health and Development for her study, “Testosterone and Cortisol Levels in Infant Health and Development.”
“Boys are more likely to be born prematurely and at a lower birth weight than girls, and boys have a higher rate of infant mortality,” Cho said. “So if boys in general are sicker than girls at an early age, why is that? What could be the possible factor we’re dealing with?”
Cho said it has been suggested that the hormone cortisol is a possible predictor of infant health and developmental outcomes. But she said preliminary research through her previous R21 project indicates that testosterone might be a more reliable biomarker for these two outcomes.
Cho's previous R21 research examined very low birth weight (VLBW) preterm infants for a period of six months. Through this new R01 grant, Cho and her research team will be able to extend the period of observation to 24 months. During this time they will track the levels of testosterone and cortisol in the infants, and observe the mothers and infants as they interact. Cho said her team plans to follow a total of 190 VLBW infants and their mothers over the next five years.
Cho explained that male infants experience a surge in testosterone during the second and third months of pregnancy, and then again during the early weeks after birth. It is speculated that a boy’s brain becomes masculinized during these periods. Cho said she wants to examine the relationship between the mother’s stress level and her baby’s testosterone level, and how this affects the infant’s cognitive, motor and language development.
“I would like to confirm that testosterone, rather than cortisol, is a more reliable biomarker of complications affecting infant health outcome, maturation and development,” Cho said. “I want to confirm that the male infant has a higher sensitivity to testosterone than the female infant. The levels are the same at birth, but males usually have a surge just after birth. I would like to identify the root of this surge of hormone level in the health and development of low birth weight infants.”
If it turns out that there is a correlation between increased testosterone levels and infant development, Cho said that discovery could lead to the development of early screening tools for a variety of behavioral disorders, such as autism.
“Once the associations between these hormones and infant health and developmental outcomes are firmly established, the study outcomes will guide us in developing a future intervention for at-risk male infants,” Cho said. “We don’t know if there is a cause-and-effect between testosterone and infant outcome, but if there is, we can develop tailored interventions.
“Today it’s all about prevention. The current diagnosis for such disorders is around age 2 or 3. But by then it’s a little bit late to correct, because the period before age 3 in brain development is the most important period. If we miss that window, we’ve lost an opportunity. With this research, perhaps we can screen infants earlier. We have a lot of opportunities to help infants if the problem is diagnosed sooner. If we bring it down a year or even six months, that is much better. Earlier diagnosis allows earlier interventions.”
Wally Carlo, MD, Director of Neonatology and Edwin M. Dixon Professor of Pediatrics at UAB, assisted Cho in the initial R21 study as well as the R01. Carlo agreed that earlier detection of potential behavioral disorders would be extremely beneficial.
“Development can be nurtured,” Carlo said. “It’s like a growing tree. It’s very easy to alter it initially, but much harder once it’s grown. That’s what we’re aiming for, to determine as early as possible what the influences of these hormones are on behavior. If we determine that hormonal levels are associated with behavioral issues in male infants, there could be interventions developed in a more timely way.
“It’s important to determine whether differences in the hormone level in premature babies explains some of the outcomes of infants. They’re born prematurely, so there are a lot of changes that occur throughout gestation that these babies are missing. We’re very interested in determining the association of hormonal imbalances – like testosterone imbalances – on the long-term outcome of babies. There is not a lot of research in this area, so this study is going to be very important. This is a great example of how the UAB School of Nursing is generating knowledge that will change the world.”
Cho said the research is especially important to her because of the physical and emotional vulnerability of infants.
“The reason I am so interested (in this work) is because babies are innocent when they are born. But because of some detrimental influences from the environment or biological factors, sometimes their development is compromised,” Cho said. “It’s my dream to help these babies get a better start to life.”
