“This is significant because we have known for some time that fetal development is influenced by the maternal stress physiology but for the first time we are showing that the sex of the fetus is also influencing the mom," says Giesbrecht, who is an assistant professor in the Department of Paediatrics in the Cumming School of Medicine and an adjunct assistant professor in the Department of Psychology in the Faculty of Arts.
The researcher is also one of the principal investigators in the newly opened Alberta Children’s Hospital Research Institute Owerko Centre for neurodevelopment and child mental health.
Study one of the largest longitudinal cohorts in Canada
The study was based on saliva samples taken from 295 healthy pregnant women in Calgary from 2010-2012. These women were participants in Alberta Pregnancy Outcomes and Nutrition (APRON) study which involved thousands of women from Calgary and Edmonton, designed to analyze the relationship between maternal nutrient status during pregnancy and maternal mental health and child health and development. It represents one of the largest and most comprehensive longitudinal cohorts established in Canada.
Giesbrecht demonstrated that stress biomarkers — basal cortisol and salivary alpha amylase (sAA) — differ by fetal sex in pregnant women. Women carrying female fetuses displayed greater cortisol and sAA secretions compared to women carrying males. Greater cortisol and sAA were also associated with lower birth weight and provides new evidence to suggest that the fetus plays a role in regulating its own growth through its effects on maternal physiology.
New insight into sex differences
“We believe these findings provide new insight into sex differences in a variety of stress-related outcomes, such as higher rates of depression in females, which are linked with increases in cortisol and sAA,” he says.
Until now, these sex-differences have been interpreted in terms of gender-specific vulnerability. The new findings suggest that differences in a variety of health and disease outcomes could originate from sex specific patterns of stress-related exposures in utero.
“Researchers interested in child development often talk about reciprocal influences — we need to start thinking about the ways these reciprocal influences may operate during pregnancy and specifically the ways that the fetus may help to shape its own development.”
The research was supported by grants from the Alberta Innovates Health Solutions, the Canadian Institutes of Health Research and the Alberta Centre for Child, Family and Community Research.