Template:Endocrine birth table

From Embryology
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Hormones Roles
  • maintains pregnancy - initially synthesized by corpus luteum, then levels maintained by placenta
  • hyperpolarizes myometrial cells (-65 mV), reduces excitability and conductivity
  • Level in plasma may fall just before parturition, definitely decreases following delivery of placenta
  • Group of steroidal hormones, peak when parturition begins
  • induce increased synthesis of actomyosin and ATP in myometrial cells
  • alter membrane potential (-50 Mv) enhances excitation/conduction
  • act to directly increase myometrial contraction
  • indirectly by increasing oxytocin from pituitary gland
  • Estriol - synthesized by fetus and placenta
  • Peptide hormone (8aa) from maternal posterior pituitary, initiation and maintenance of labour (synthetic form labour induction)
  • myometrium sensitivity to oxytocin (increased by estrogen, decreased by progesterone)
  • stimulus for release - mechanical stimulation of uterus, cervix and vagina (ethanol inhibits release)
  • hydroxy fatty acids - sythesized by placenta, amniotic fliud contains mainly PGF2 alpha, causes myometrial contraction (also in maternal plasma)
  • prostaglandin F2 alpha (PGF2 alpha) and prostaglandin E2 (PGE2) - used to induce labour (intravenous, oral, intravaginal, intraamniotic)
  • Aspirin inhibitor of PG synthesis - leads to increased duration of pregnancy
Endocrine Birth