The organ that develops in the uterus during pregnancy and that link the blood supplies of mother and baby. The placenta develops from the chorion. It is firmly attached to the lining of the woman’s uterus and is connected to the baby by the umbilical cord. It is expelled shortly after the baby is born. The placenta transfers oxygen and nutrients from the mother’s circulation into the fetus’s circulation, and removes waste products from the fetus’s blood into the mother’s blood for excretion by her lungs and kidneys. It also produces hormones such as oestrogen, progesterone, and human chorionic gonadotrophin (HCG). High levels of HCG appear in the woman’s urine during early pregnancy, and detection of them in the urine forms the basis of pregnancy tests.


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