Meyer - Maternal Adaptation to Pregnancy

Question 1

What is human placental lactogen (HPL)? Actions?

Answer 1

• Polypeptide with no carbohydrate component; similar to GH and prolactin
• Rate of rise is steady during entire pregnancy
  1. Not specific for pregnancy: (+) titers with bronchogenic carcinoma, hepatoma, lymphoma, and pheochromocytoma
  2. Titer low in trophoblastic disease
• ACTIONS: anti-insulin; NOT required for successful pregnancy
  1. Lipolysis: INC circulating free fatty acids for mom’s metabolic needs, leaving glu for baby
  a. Any period of relative starvation: mom is NOT getting carb supply, so lipids go up -> normal physiologic response
  2. INH of glucose uptake, INC blood sugar, a readily-available energy source for the fetus
• Gestational diabetes: pregnancy is a diabetagenic state, mostly because of this hormone
• NOTE: placenta is basically an endocrine organ, and makes a lot of hormones
• Discriminatory zone
• 6,500 mIU/mL
• Sac on abdominal scan
• 2,400 mIU/ml
• Sac on vaginal scan
• Affected by anything that affects the size/growth of the placenta
• Similar levels in both blood and urine, and it is very sensitive: logarithmic (almost) INC in early pregnancy: makes monitoring of pregnancy possible (if you don’t see normal INC, you may wonder about the normalcy of the pregnancy)
• Ectopic pregnancy: not going to develop, or produce its hormones normally – hCG helps to diagnose pregnancies early (US has become very helpful in diagnosing these; can intervene with various techniques, including with medication; no longer strictly a surgical disease)

Question 2

Why is pregnancy a diabetogenic state?

Answer 2

• Mostly because of of HPL (similar actions to GH: INC lipolysis, and decreased insulin sensitivity)
• Gestational diabetes

Question 3

What is human chorionic gonadotropin (hCG)? Actions?

Answer 3

• Glycoprotein secreted by syncytiotrophoblast with two non-covalently bonded subunits
  1. Alpha: similar to FSH, LH, TSH
  2. Beta: hormone specific unit
• INC titers w/multiple gestations, erythroblastosis, hydatidiform mole, choriocarcinoma
• DEC titers with ECTOPIC PREGNANCY and death of conceptus
• ACTIONS: prolongs life of corpus luteum
  1. INC steroid production
  2. Diagnostic test for pregnancy