Birthweight and the Placenta

The weight and shape of the placenta, along with the baby’s birth weight, are important measurements of how well the baby developed in the womb. The size and shape of the placenta are affected by environmental exposures the mother faces during pregnancy. Access to quality foods and a well-balanced diet, exposure to toxic stress and certain environmental chemicals all play a role in the development of the placenta. The placenta serves as both protection and nutritional provider for the developing baby. For mothers who lack access to quality food, the placenta increases in size in order to better protect the fetus and to better extract nutrients.

The circulation within the placenta is central to uterine and umbilical blood flows, and is therefore an important player for the success of pregnancy. The foods the mother is able to eat during pregnancy will determine how well the placenta is able to transport nutrients and oxygen to the developing baby.

When the placenta increases in size to better absorb nutrients from the mother’s diet when nutrition is limited, it increases the capacity to transfer nutrients and, for example, support brain growth. However, this diverted blood supply can also threaten the development of other organs. The developing organs that receive less blood within the womb are at a greater risk of developing a chronic disease later in life. So the increase in placental growth and size impacts future development of the baby.  Additionally, the placenta requires nutrition itself, and with its increased size some of the nutrition meant for the fetus will be used to sustain its larger size.

While large placentas are associated with greater risk of chronic disease, small placentas and small or thin infants, indicate malnourishment and a lack of oxygen supply during development in the womb. Small placentas are also associated with increased risk of chronic disease later in life. The goal is for balanced nutrition throughout pregnancy, to support healthy growth that leads to a healthy birthweight - considered to be around eight to nine pounds.

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