Body water changes during pregnancy

An increase in body water accounts for a large percentage of weight gain exhibited during a natural pregnancy. This occurs as a result of placental and foetal development, the formation of amniotic fluid and an increased maternal plasma 

Three groups of investigators have used deuterium oxide to follow the reduction in maternal total body water from late pregnancy to post-partum [264— 266]. Mean water loss was approximately 6 1 though the range was large (0-14.2 1) and the number of women studied was few. 

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