Obstetrics & Gynecology>>>>>The Puerperium, Lactation, and Immediate Care of the Newborn
Question 4#

A 30-year-old G5P3 has undergone a repeat cesarean delivery. She wants to breastfeed. Her past medical history is significant for hepatitis B infection, hypothyroidism, depression, and breast reduction. She is receiving intravenous antibiotics for endometritis. The baby latches on appropriately and begins to suckle.  

In the mother, which of the following is a response to newborn suckling?

A) Decrease of oxytocin
B) Increase of prolactin-inhibiting factor (PIF)
C) Increase of hypothalamic dopamine
D) Increase of hypothalamic prolactin
E) Increase of luteinizing hormone—releasing factor

Correct Answer is D

Comment:

The normal sequence of events triggered by suckling is as follows: through a response of the central nervous system, dopamine is decreased in the hypothalamus. Dopamine suppression decreases production of PIF, which normally travels through a portal system to the pituitary gland; because PIF production is decreased, production of prolactin by the pituitary is increased. At this time, the pituitary also releases oxytocin, which causes milk to be expressed from the alveoli into the lactiferous ducts. Suckling suppresses the production of luteinizing hormone—releasing factor and, as a result, acts as a mild (but not reliable) contraceptive (because the midcycle surge of luteinizing hormone does not occur).