Pregnancy, Parturition, Labor, and Lactation

Question 1

General Adaptive changes to the maternal system

Answer 1

Increase:

• Plasma Volume (aldosterone)
• red cells (erythropoietin secretion)
• renal blood flow
• heart rate
• tidal volume (P4 medullary respiratory centers)
• weight gain

Decreased:

• gastric motility
• esophageal sphincter tone
• osmolality

Question 2

Changes in Pituitary Gland

Answer 2

increased size due to estrogen stimulated hypertrophy and hyperplasia of lactotrophs (supports the secretion of prolactin)
increased:
prolactin
oxytocin
ACTH
Decreased FSH/LH

Question 3

Changes in the Thyroid

Answer 3

Increase in size due to the hCG (identical alpha chains)

increase in total T3 and T4 (no change in free T3/T4 because of estrogen stimulation to the liver increasing TBG

Question 4

Changes in Pancreas

Answer 4

Estrogen and hPL/PRL cause hyperplasia and hypertrophy of the Beta Cells
Beta cells become more sensitive to glucose because of hPL/PRL (increase secretion of insulin to glucose stimulus)

Question 5

Changes in the adrenal cortex

Answer 5

Increase response to ACTH
Increase cortisol secretion (due to increased concentration of ACTH and hypersensitivity)
increased liver production of CBG
increase in aldosterone (estrogen –increases renin substrate in liver– increased renin– increased aldosterone)

Question 6

Corticotropin Releasing Hormone (CRH)

• produced by
• stimulated by

Answer 6

CRH is:
produced by syncytiotrophoblasts/ cytotrophoblasts
stimulated by glucocorticoids (hypothalamic CRH is inhibited by glucocorticoids)

Question 7

Progesterone

• produced by?
• function during pregnancy

Answer 7

Progesterone is

• produced by the placenta and returns to maternal circulation
• functions to block myometrial contractions by inhibiting OT receptors, syn. of CAP, and inhibiting COX-2, NF-KB (inflammatory mediators)

Question 8

Estrogens

• synthesized from?
• function during pregnancy

Answer 8

Estrogen is

• synthesized in the placenta from 16-DHEA from the fetus and secreted into maternal circulation
• estrogen is more active in the myometrium. Promotes labor and contractions by increasing myometrial OT receptor number, increasing the gap junctions (leading to increased contractility) syn. of CAP, recruits MMP to remodel cervix (cervical ripining)

Question 9

Onset of Parturition

• removal of
• roles of the fetus
• Key hormones

Answer 9

Parturition begins with the removal of the progesterone block. Functionally, this changes the dominance of hormones to estrogen dominant which favors myometrium activity.

• The fetus produces hormones necessary for parturition as well as the mechanical stretch of the uterus (leading to myometrial contractions)
• Key hormones: CRH (gets everything rolling), PG- increase the concentration of Ca++ (stimulates contrations) and increases the gap junction formation between myometrial cells, OT- also directly leads to contractions

Question 10

Pre-term labor?

Answer 10

Delivery prior to 37 weeks

Question 11

Pre-eclampsia/Eclampsia

• causes
• symptoms
• when does it occur

Answer 11

new onset hypertension and proteinuria

• dysfunctional placentation
• edema, rapid weight gain, Increase in BLOOD PRESSURE, seizures
• usually seen after the 20th week of pregnancy

Question 12

Oxytocin
-MOA
-clinical uses
-Routes of administration
-

Answer 12

Oxytocin
-MOA: OT receptors (GPCR- Gq) numbers increase in uterine smooth muscle– increases sensitivity to OT– increased intracellular Ca++ levels
-Clinical uses: labor induction, augments abnoral (protracted) labor
-Routes: IV via infusion pump for labor induction. dose is increased to simulate the normal progression of labor
IM: controls postpartum bleeding

Question 13

Oxytocin: adverse drug reactions

Answer 13

Oxytocin- Adverse Drug reactions

• Excessive stimulation of uterine contraction before delivery–> fetal distress, placental abruption, or uterine rupture
• hyperstimulation: contractions that last for 2 or more minutes
• tachysystole: more than 5 contractions in 10 minutes
• activation of the vasopressin receptor resulting in excessive fluid retention or water intoxication (hyponatremia, heart failure, death)
• hypotension

Question 14

Prostaglandins

• effects on uterine muscle
• clinical uses
• administration

Answer 14

Prostaglandins (PGE2) induce contractions
Clinical uses:
-cervical ripening
-first step in inducing labor
-administer Prostaglandins as an insert or a gel directly into vagina. It rapidly enters circulation and small amounts enter the uterus/
oral PGE2 is as efficient as IV oxytocin

Question 15

Adverse reactions to Prostaglandins

Answer 15

Adverse reactions to PG include:

• N/V/D (GI discomfort)
• potent vasodilation
• Tachysystole (increased when used in combo with Oxytocin– increased sensitivity to OT)

Question 16

Hydroxyprogesterone caproate

• uses
• administration route

Answer 16

Hydroxyprogesterone caproate
used to reduce the risk of preterm labor (can be given as early as 16 weeks)
administered IM or vaginally

Question 17

COX inhibitors

• MOA
• Adverse reactions

Answer 17

COX inhibitors (Indomethacin)

• MOA- prevents the formation of PG from arachidonic acids
• for preterm labor at 24-36 weeks

Adverse Reactions
Maternal- GI distress
Fetal- premature constriction of the ductus arteriosus, oligohydramnios (decreased fetal urine output leading to a decreased amniotic fluid volume)

Question 18

Ca++ Channel Blockers

-MOA

Answer 18

nifedipine:
blocks Ca++ channel. Inhibits the release of intracellular calcium from the SR–inhibition of myosin-light chain phosphorylation– relaxation of myometrium

Question 19

Mifepristone
MOA:
Uses:
Side Effects:
Route of administration

Answer 19

AKA RU486
MOA: synthetic steroid progesterone receptor antagonist. Terminates pregnancy by promoting uterine contractions (oxytocic like actions)
Uses: abortifacient during 1st and 2nd trimesters. Dose is much larger than that needed to induce labor
Side Effects: abdominal pain and bleeding
Route: Oral preferred, vaginal is also available