Parturition/Lactation

Question 1

What are the three phases of parturition?

Answer 1

1- initiation of labor 2- delivery of fetus and placenta, 3- uterine contraction to revert back to pregravid size

Question 2

What are the major factors of parturition?

Answer 2

estradiol, PGE2 and PGF2a, and Oxytocin

Question 3

What does PGE2 do in non-pregnant women? pregnant?

Answer 3

relaxes myometrium; uterus contractions (both PGF2a and PGE2

Question 4

What does estradiol do during parturition?

Answer 4

induces PGE2 and PGF2a production in fetal membrane and myometrium and oxytocin receptors in the myometrium

Question 5

What do PGs do during parturition?

Answer 5

initiate uterine contractions, activates stretch receptors in cervixmyometrium (stimulus from fetal head, huge # of stretch and pain fibers in both)

Question 6

What does oxytocin do?

Answer 6

maintains uterine contractions and stimulates PG production

Question 7

What is the mechanism for the onset of labor?

Answer 7

P decreases myometrial contraction during pregnancy, reduced calmoudulin and placental PGE2 synthesis and degradation of PG via PG dehydrogenase; increase E2 near term override P inhibition and stimulate PGE2/PGF2a synth-> uterine contraction and activate cervical collagenase-> soften cervix; 2d half preg. uterus undergoes periodic slow and weak rhythmic contractions (Braxton-Hicks); rate and intensity increases til 2nd phase

Question 8

What causes labor pain?

Answer 8

massive contractions excite uterine pain fibers

Question 9

how does the fetal head assist in onset of labor?

Answer 9

stretches soft cervix-> initiation of neurogenic stimulus to hypothalamus causing oxytocin release-> stimulates placental synth. of contractions->further stretching of cervix-> positive neurogenic feedback loop to oxytocin secretion-> stringer contractions-> leads to fetal exit->10-45 min after delivery ->expulsion of placenta (350mL blood loss)

Question 10

How does estradiol work in mammary gland development?

Answer 10

induces lactotrope hyperplasia, oxytocin receptors in alveolar and ductal myoepithelial cells, stimulates prolactin synthesis; also reduces dopamine synth and D2 receptor level in lactotropes leading to disinhibition of prolactin synth and secretion

Question 11

What hormones are necessary for ductal development?

Answer 11

E2 + GH + prolactin

Question 12

What hormones are needed for lobulo-alveolar development?

Answer 12

P + E2 + Prolactin + GH + Insulin + IGF-I + Thyroxine + Cortisol

Question 13

What role does dopamine play in mammary gland development for lactation?

Answer 13

D from arcuate nucleus fo hypothalamus via D2R activates Gai which inhibits andenylate cyclase activity; Prolactin synth decreases due to low cAMP, secretion decreases due to low intracellular [Ca]

Question 14

What role does prolactin play in galactopoeisis?

Answer 14

stimulates synth of major milk proteins (B-casein 60% and whey 40%-including a-lactoalbumin, b-lactoglobulin, Ig, albumin, and UDP-galactosyl transferase; induces E and prolactin receptors in mammary gland epithelial cells

Question 15

What else is required besides prolactin for galactoporeisis?

Answer 15

cortisol at physiological levels for expression of transcription factors for milk protein synth,

Question 16

Why does galactopoiesis only occur late in gestation even though P is available?

Answer 16

P antagonizes alveolar cells prolactin receptor by inhibiting up regulation of prolactin receptor, reducing estrogen binding, competing for binding of glucocorticoid receptor; high levels of E2 interferes with prolactin binding to its receptors-> inhibits terminal differentiation of alveolar epithelial cells

Question 17

When does breast engorgement and milk secretion occur?

Answer 17

2-4 days postpartum when steroids are sufficiently cleared from maternal blood

Question 18

What stimulus is needed to induce Milk-let-down reflex?

Answer 18

suckling-induced sensory signals from nipple and areola reach SON and PVN-> release of oxytocin-> contractions of myoepithelial cells surrounding ducts and alveoli-> milk flow through the duct (also needed for secretion of prolactin during lactation)

Question 19

What is first milk?

Answer 19

colostrum, high amounts of B-carotene, proteins, IgA, lactoferrin and relatively lower amounts of lactose

Question 20

What is the composition of mature human milk?

Answer 20

Protein 0.8-0.9%, Carb 6.8-7.2%, Fat 3-5%, Mineral 0.2% and water

Question 21

What are the proteins in mature human milk?

Answer 21

B-casein, a-lactalbumin, lactoferrin, IgA, lysozyme, and albumin

Question 22

What are the carbs in mature human milk?

Answer 22

lactose but 30 or more oligosaccharides also present

Question 23

What are the fats in mature human milk?

Answer 23

Triglyc; most common are aplmitic and oleic

Question 24

What are the minerals in mature human milk?

Answer 24

Na, K, Ca, Cl, Mg, P, Fe, Cu, and Zn

Question 25

What does lactoferrin do for the baby?

Answer 25

inhibits growth of iron dependent bacteria in GI tract (coliforms and yeasts requiring iron too)

Question 26

What does secretory IgA do for infant?

Answer 26

protect infant from viruses and B, specifically those that baby, mom and family are exposed to; helps protect against E coli and possibly allergies; other immunoglobins IgG and IgM help protect against B and viral infections

Question 27

What does lysozyme do for the baby?

Answer 27

protects against E. coli and salmonella; promotes growth of healthy intestinal flora and has anti-inflammatory functions

Question 28

What does bifidus factor do for the baby?

Answer 28

supports growth of lactobaccilus-> beneficial B that protects baby against harmful B by creating acidic environment

Question 29

What specifically does suckling induced prolactin do? Suckling induced oxytocin?

Answer 29

stimulates milk synthesis; let down of milk

Question 30

What causes galactopoeisis to cease?

Answer 30

withdrawal of breastfeeding; maintained as long as stimulation of breast is continued

Question 31

What are the advantages of breastfeeding for the infant?

Answer 31

species specificity, optimal growth of infant, breast milk perfectly matches infants daily requirement, long chain FA development; antimicrobial factors protect against illness, prevention of acute illness (diarrhea, necrotizing enterocollitis, meningitis, UTI, and respiratory illness- pneumonia, bronchitis, otitis), protect against chronic illness- juvenile diabetes mellitus and ulcerative colitis; protection against allergic disease, improved cognitive development, reduced risk SIDS, ready source of comfort and security

Question 32

What are the maternal advantages of breastfeeding?

Answer 32

more rapid uterine involution, early return of pre-pregnancy weight, prolonged post-partum anovulation (PRL inhibits GnRH), conectption 1st 6 mo, less menstrual blood loss, cost saving, enhance interaction, convenience and ease of feeding, and reduced risk of : post menopausal hip Fx, pre-menopausal breast cancer, ovarian cancer

Question 33

What are infant contraindications to breast feeding?

Answer 33

prematurity, IUGR and < 6lbs, multiple births, cardiac disease, respiratory distress, infection esp mouth, lactose intolerance, neurologic problem, neonatal jaundice, latch-on problems, reluctant nurses, dysfunctional suckling, and oral anatomic abnormality: cleft lip/palate, micrognathia

Question 34

What are maternal contraindications to breast feeding?

Answer 34

variation in breast appearance (hypoplastic, tubular), excessive or unrelieved postpartum breast engorgement, previous breast surgery or absess, previous problem with milk synthesis, severe or chronic sore nipples: mechanical trauma, yeast or bacterial infection, sensitive/dry skin and consequent skin crack, flat or inverted nipples affecting infant latch on/milk removal, perinatal complication (high bp/infection), underlying systemic illness (cystic fibrosis, diabetes, heart disease), failure of milk production in first 7 days may be sign of Sheehans, or extremes in maternal age (38)

Question 35

What is galactorrhea?

Answer 35

secretion of milky fluid from breast at times other than pregnancy

Question 36

Where can the problem exist in galactorrhea?

Answer 36

activation of afferent neuroendocrine limb, decreased dopamine release or function, prolactinomas of anterior pituitary or ectopi PRL production, elevated TRH during hypothyroidism and chronic renal failure

Question 37

What are examples of activation of afferent neuroendocrine limb in galactorrhea?

Answer 37

stimulation by suckling, excessive manual stimulation, heroes zoster of thoracic nerves, spinal cord lesions and breast surgery

Question 38

What are examples of decreased dopamine release or function causing galactorrhea?

Answer 38

drugs like phenothiazines, morphine, amphetamines, estrogens can interfere with dopamine metabolism

Question 39

What are examples of prolactinemias of anterior pituitary or ectopic PRL production in galactorrhea?

Answer 39

tumors- renal, liver and uterine fibroids

Question 40

What are examples of elevated TRH causing galactorrhea?

Answer 40

in hypothyroid pts sometimes exhibit hyperprolactinemia with remarkable pituitary enlargement due to thryotrope hyperplasia; thyroid replacement with reduction in pituitary enlargement and normalization of PRL

Question 41

What is Sheehan syndrome?

Answer 41

major hemorrhage during postpartum period, can result in ischemia of affected pituitary regions leading to necrosis-> infarction of PRL cells