The Placental Exposome: Placental Determinants of Fetal Adiposity and Postnatal Body Composition

Offspring of obese and diabetic mothers are at increased risk of
beingborn with excess adiposity as a consequence of their
intrauterineenvironment. Excessive fetal fat accretion reflects
additional placentalnutrient transfer, suggesting an effect of the
maternal environment onplacental function. High plasma levels of
particular nutrients in obeseand diabetic mothers are likely to be
the important drivers of nutrienttransfer to the fetus, resulting
in excess fat accretion. However, notall offspring of obese and
diabetic mothers are born large forgestational age and the
explanation may involve the regulation ofplacental nutrient
transfer required for fetal growth. The placentaintegrates maternal
and fetal signals across gestation in order todetermine nutrient
transfer rate. Understanding the nature of thesesignals and
placental responses to them is key to understanding thepathology of
both fetal growth restriction and macrosomia. The overalleffects of
the maternal environment on the placenta are the product ofits
exposures throughout gestation, the ‘placental
exposome’.Understanding these environmental influences is important
as exposuresearly in gestation, for instance causing changes in the
function ofgenes involved in nutrient transfer, may determine how
the placenta willrespond to exposures later in gestation, such as
to raised maternalplasma glucose or lipid concentrations.
Longitudinal studies arerequired which allow investigation of the
influences on the placentaacross gestation. These studies need to
make full use of developingtechnologies characterising placental
function, fetal growth and bodycomposition. Understanding these
processes will assist in thedevelopment of preventive strategies
and treatments to optimise prenatalgrowth in those pregnancies at
risk of either excess or insufficientnutrient supply and could also
reduce the risk of chronic disease inlater life.