Endocrinology and Pregnancy

Question 1

What happens during implantation and what is required?

Answer 1

• Implantation:
  o Trophoblastic invasion of the maternal vascular system establishes the hemochorial placenta
   Extravillous cytotrophoblast: invasion of spiral arteries
   Syncytiotrophoblast
  o Growth factors
  o IL 1 beta stimulates invsation
  o Chorionic villi
   Inner core of cytotrophoblast: peptide hormones
   Syncytiotrophoblas:peptide and steroid hormones

Question 2

HCG
subunits, when does it peak, what does it do?

Answer 2

o Alpha subunit: 92 amino acids; homologous to TSH, LSH, FSH
o Beta subunit: 145 amino acids; similar to LH
o Peaks at 10 weeks (100,000)
o Maintains corpus luteum function to support progesterone production

Question 3

Estrogen
- major type in pregnancy. functions in pregnancy

Answer 3

o Estriol is major estrogen in pregnancy
o Estradiol higher in maternal serum due to higher affinity for SHBG and reduced clearance
o Increase uterine blood flow; prepare for lactation, stimulates production of SHBG

Question 4

Progesterone in pregnancy

Answer 4

• Progesterone:
  o Chorioamniotic membrane strength; delay cervical ripening, immunosuppressant

Question 5

Carbohydrate metabolism in pregnancy

Answer 5

o Beta cell hypertrophy and hyperplasia with increased insulin secretion in 1st trimester
o Decreased insulin requirements in 1st trimester
o Diabetogenic in latter ½:
 hPL, placental growth hormone; reduced tissue sensitivity to insulin
o Glucose transported to fetus by facilitated diffusion
o Maternal fed state: hyperglycemia, hyperinsulinemia, and hypertriglyceridemia

Question 6

Hormones requires for placental angiogenesis

Answer 6

• Placental angiogenesis: - proteins appear to be involved in PEC
  o Proangiogenic: VEGF, PlGF
  o Anti-angiogenic: sFlr1, sEng

Question 7

CRH and pregnancy

Answer 7

• CRH: 41 amino acid peptide; synthesized by cyto/syncytiotrophoblast, chorion, amnion, and decidua
  o Detectable by 7-8 weeks and rises progressively through gestation (peaking in labor)
  o In vitro stimulates release of PGE and PGF2 alpha (may play role in initiation of labor)

Question 8

Oxytocin and pregnancy

Answer 8

• Oxytocin: nonapeptide synthesized by syncytiotrophoblast; receptors increase in 2nd stage of labor
  o Pulsatile secretion

Question 9

Prolactin in pregnancy : source and functions

Answer 9

• Prolactin: 2 sources:
  o Pituitary – estrogen stimulates growth of pituitary; primes for lactation
   Declines to normal 3-4 weeks pp unless breastfeeding
  o Decidua – major source of amniotic fluid prolactin; identical to pituitary form; through to regulate solute and water transport in amniotic compartment