Placental Aging: Association Between the Placental Epigenetic Clock and Maternal Smoking During Pregnancy Open Access

Abstract

Gestational age is the current standard used by physicians to predict the due date of an infant and customize patient care. Understanding age at birth is necessary, as premature birth is a factor contributing to adverse respiratory outcomes, decreased neurological development, and increased mortality. Epigenetic age, based on DNA methylation at specific genomic regions, has been used as a marker of biological aging in adult populations, and an accelerated epigenetic age (compared to chronologic age) has been linked to morbidity and mortality. These biomarkers, though, have not been applied as extensively in pediatric or neonatal research. Recently a novel method for estimating epigenetic gestational age from placental DNA methylation levels, a placental epigenetic clock, has been developed. Our objective was to investigate the relationship between maternal smoking and acceleration of the placental epigenetic clock as well as the association between DNA methylation acceleration and birthweight. Pregnant women were recruited and enrolled as a part of The Behavior and Mood in Babies and Mothers (BAM BAM) study, and this analysis included 89 participants (mothers/infant pair), 35 of which did not smoke at all during pregnancy and 54 which smoked at some point during pregnancy. The difference between actual gestational age and placental epigenetic age was found to be smaller in participants who did not smoke at any time during pregnancy compared to participants who did smoke during pregnancy. An increasing epigenetic age acceleration was also associated with decreased birthweight; for each 1 week of epigenetic acceleration, birthweight was decreased by 113g (p=0.012). These results suggest smoking during pregnancy induces a reduced biological aging of the placenta, which is associated with birthweight, and indicates a need for additional analyses to understand the functional impact of altered placental aging.

Table of Contents

Introduction…………………………………………………………………………….. 1

Methods………………………………………………………………………………… 5

Results………………………………………………………………………………….. 8

Discussion……………………………………………………………………………… 9

References……………………………………………………………………………… 12

Tables and Figures

Table 1…………………………………………………………………………………. 15

Table 2…………………………………………………………………………………. 16

Figure 1………………………………………………………………………………… 17

Figure 2………………………………………………………………………………… 18

Table 3…………………………………………………………………………………. 19

Figure 4………………………………………………………………………………… 20

Figure 5………………………………………………………………………………… 21

Table 4…………………………………………………………………………………. 22

About this Master's Thesis

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School	Rollins School of Public Health
Department	Environmental Health
Degree	M.P.H.
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health
Keyword	Epigenetics Epigenetic Clock Maternal Smoking
Committee Chair / Thesis Advisor	Carmen Marsit, Emory University

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