Breastfeeding

Question 1

Mammary gland development during pregnancy

Answer 1

Increased levels of hormones from placenta near the end of pregnancy: E, P, and human placental lactogen

Mild stimulation of release of PRL from ant pit

• PRL contributes just a little to development
• PRL inhibited by E and P from producing milk

Question 2

Hormonal changes after delivery

Answer 2

Removal of placental source of E + P

• Prolactin secretion increases
• Milk secretion within days

Question 3

Neural/hormonal regulation of let down reflex

Answer 3

Suckling = mech stimulation of nipples
-sensory neural signals to hypothalamus

1. inhibits PIH (dopamine) allowing release of PRL in ant pit
   - via blood to mammary glands
   - stimulates alveolar cells to secrete milk
2. Stimulates neurons in hypothalamus causing release of oxytocin in post pit
   - via blood to mammary glands
   - contraction of myoepithelial cells surrounding glandular cells
   - milk ejection

Question 4

What factors can inhibit release of milk?

Answer 4

Stress, distraction, embarrasment, fear, anxiety

Sympathetic vasoconstriction in stress inhibits access of myoepithelium to oxytocin

Question 5

What factor can increase milk release?

Answer 5

conditioned stimuli: sight, sound, or smell of baby

Question 6

What do the prolactin levels look like

Answer 6

Pretty high right at birth, but then go down

Peak and fall with nursing sessions

Physically, not hormonally, controlled after birth

Question 7

First phase of breast milk

Answer 7

Colostrum (first few days)

• thicker than milk
• creamy or yellowish
• lots of nutrients (liquid gold) –> high prot, low fat, easy to digest
• passive immunity (antibodies from mom) –> IgA protects digestive tract
• natural laxative –> removal of meconium = tar-like poop made before birth

Note: IgA is present in other phases of milk too

Question 8

Phase 2 of breast milk

Answer 8

Transitional milk (within 2-5 days)

• color = bluish white
• more calories than colostrum

Question 9

Phase 3 of breast milk

Answer 9

Mature milk (within 2 weeks)

• fore-milk is water and protein rich
• hind-milk has more fat

Question 10

Breast feeding and birth control

Answer 10

• PRL inhibits GnRH
• Decreases FSH and LH
• No menstrual cycles –> transient amenorrhea
• Natural contraceptive sometimes
• Ovulation and cycles can resume within 6-9 months even with continued nursing –> associated with less frequent nursing

Don’t use oral estrogens for contraception –> passes to baby with potential deleterious effects on growth –> also inhibits milk production