Maternal rotating night shift work before pregnancy and offspring stress markers

Recent studies suggest an intergenerational influence of stress such that maternal exposure even before pregnancy could impact offspring health outcomes later in life. In humans, investigations on the impact of maternal stressors on offspring health outcomes, including stress-sensitive biomarkers, have largely been limited to extreme stressors. Prior studies have not addressed more moderate maternal stressors, such as rotating night shift work, on offspring stress markers in young adulthood.

We investigated the association between maternal rotating night shift work before conception and offspring salivary cortisol and alpha amylase (sAA) patterns in young adulthood among mothers enrolled in the Nurses' Health Study II (NHSII) and their offspring participating in the Growing Up Today Study 2 (GUTS2). Our sample included over 300 mother-child pairs where, between 2011 and 2014, the children provided 5 saliva samples over the course of one day. We used piecewise linear mixed models to compare awakening responses, overall slopes as well as several other diurnal patterns of cortisol and sAA between offspring born to shift working versus non-shift working mothers.

Offspring born to shift working mothers had a flattened late decline in cortisol (percent differences in slope (%D): 2.1%; 95%CI: 0.3, 3.8) and their sAA awakening response was steeper (%D -37.4%; 95%CI: -59.0, -4.4), whereas sAA increase before bedtime appeared less pronounced (%D -35.9%; 95%CI: -55.3, -8.3), compared to offspring born to mothers without shift work. For cortisol, we observed a significant difference in the Area Under the Curve (AUC) (%D 1.5%; 95%CI: 0.3, 2.7) with higher AUC for offspring of mothers who worked rotating night shifts. In offspring-sex-stratified analyses we found differences primarily among males.

Our results provide some - albeit modest - evidence that maternal rotating night shift work-a moderate stressor-influences offspring stress markers. Future studies with larger samples sizes, more detailed exposure assessment (particularly during maternal pregnancy), and multiple offspring biomarker assessments at different developmental stages are needed to further investigate these associations.