Definition - What does Decidua mean?

Decidua is the uterine lining (or endometrium) when a woman is pregnant.

After a fertilized egg has implanted in the endometrial connective tissue, the cells of the endometrium mature and assume specific functions such as the formation of the placenta, hormone release, supplying of blood and providing strength to the uterus. These changes are driven mainly by the hormone progesterone.

Any defect in the formation or maturation of the decidua can lead to infertility or pregnancy-related complications such as miscarriage, premature birth, and preeclampsia.

FertilitySmarts explains Decidua

The decidua is categorized into three zones based on its position in relation to the embryo. When the fertilized egg is embedded within the endometrium, the layer of endometrium that lies beneath the embryonic sac becomes the decidua basalis and contributes to the formation of the maternal side of the placenta. The endometrium overlying the embryo is known as the decidua capsularis. The rest of the endometrium of the uterus is the decidua parietalis.

Decidua is the maternal interface of the embryo that regulates the interactions between the mother and the fetus. Functions of the decidua include:

  • Providing nutrition and oxygen to the fetus
  • Removal of carbon-dioxide and waste products from the fetus
  • Providing protection to the fetus from maternal immune cells and some infections / toxins
  • Production of hormones and growth factors (eg; cortisol, CRF, GnRH, prolactin, relaxin, vascular endothelial growth factor)

A deficiency in the formation of the decidua, the decidua basalis to be specific, can give rise to placental abnormalities such as placenta accreta, where the placenta grows too deep into the uterine tissue and attaches to the muscle cells in the uterine myometrium.

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