Pregnancy and Lactation: Physiological Adjustments, Nutritional Requirements and the Role of Dietary Supplements
Mary Frances Picciano
Abstract
Nutritional needs are increased during
pregnancy and lactation for support of fetal and infant growth and
development along
with alterations in maternal tissues and
metabolism. Total nutrient needs are not necessarily the sum of those
accumulated
in maternal tissues, products of pregnancy and
lactation and those attributable to the maintenance of nonreproducing
women.
Maternal metabolism is adjusted through the
elaboration of hormones that serve as mediators, redirecting nutrients
to highly
specialized maternal tissues specific to
reproduction (i.e., placenta and mammary gland). It is most unlikely
that the heightened
nutrient needs for successful reproduction can
always be met from the maternal diet. Requirements for energy-yielding
macronutrients
increase modestly compared with several
micronutrients that are unevenly distributed among foods. Altered
nutrient utilization
and mobilization of reserves often offset enhanced
needs but sometimes nutrient deficiencies are precipitated by
reproduction.
There are only limited data from well-controlled
intervention studies with dietary supplements and with few exceptions
(iron
during pregnancy and folate during the
periconceptional period), the evidence is not strong that nutrient
supplements confer
measurable benefit. More research is needed and in
future studies attention must be given to subject characteristics that
may influence ability to meet maternal and infant
demands (genetic and environmental), nutrient-nutrient interactions,
sensitivity
and selectivity of measured outcomes and proper use
of proxy measures. Consideration of these factors in future studies of
pregnancy and lactation are necessary to provide an
understanding of the links among maternal diet; nutritional
supplementation;
and fetal, infant and maternal health.
Witma Aptriyana
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