PROJECT SUMMARY: As demonstrated by a growing number of studies, stress
experienced during pregnancy can lead to significant long-term health problems for
mothers and their infants. One biological mechanism that has been identified in
heightening a woman’s risk for developing stress-related health complications during
pregnancy is the stress hormone cortisol. Further, certain genetic factors, such as the
short allele of the (serotonin transporter) 5-HTTLPR gene, have been implicated in
increasing one’s cortisol response to stressors in the environment. The impact of these
two biomarkers of stress is highly significant in fetal development, as maternal cortisol
readily crosses the placenta, potentially causing the fetus to become overly sensitive to
environmental stressors after childbirth. Indeed, some studies have shown early life
stressors (e.g., socioeconomic adversity, harsh parenting) to accelerate the shortening of
telomeres (DNA segments that measure disease risk and biological aging) in children.
Yet, few studies have identified pre- and postnatal determinants of infant telomere length
among low-income, chronically stressed families. The objective of the proposed study is
to prospectively examine whether prenatal maternal and fetal cortisol levels and the 5-
HTTLPR genotype of low-income pregnant mothers are predictive of changes in infant
telomere length over the first six months postpartum and whether certain maternal and
infant characteristics (e.g., exposure to chronic stressors, maternal sensitivity towards
their infants) influence these outcomes. A total of 125 low-income mothers will be recruited
during pregnancy to provide saliva samples that assess their prenatal cortisol levels and
5-HTTLPR genotype. Mothers will also collect their infant’s hair (within one week after
birth) to assess fetal cortisol levels, as well as their infant’s saliva to assess for changes
in telomere length from birth to six months postpartum. It is hypothesized that heightened
prenatal maternal and fetal cortisol levels and the short allele 5-HTTLPR genotype in
mothers will be associated with accelerated shortening of infant telomere length from birth
to six months postpartum, and that telomere length will be moderated by certain maternal
and infant characteristics (e.g., greater maternal exposure to chronic stressors, less
maternal sensitivity towards their infant’s needs). This hypothesis has been formulated
from preliminary data collected by the principal investigator and study collaborators. The
results of the proposed work have substantial public health implications in advancing our
understanding of how prenatal biological mechanisms contribute to the intergenerational
transmission of stress outcomes among low-income pregnant mothers and their infants
that can have lifelong consequences for the offspring’s health and disease risk. Such
findings will also help to identify potential avenues for prevention and treatment, during
critical periods of development, to optimize health outcomes for mothers, their children,
and subsequent generations.