A multiparous client, 28 hours after a cesarean birth, who is breastfeeding, has severe cramps or afterpains.The nurse explains that these are caused by:

Choice A rationaleAccumulation of flatulence can cause abdominal discomfort after a cesarean birth, but it does not directly stimulate uterine contractions leading to afterpains. Afterpains are specifically related to the involution of the uterus, not gastrointestinal motility.Choice B rationaleBreastfeeding stimulates the release of oxytocin from the posterior pituitary gland. Oxytocin is a powerful uterotonic hormone that causes the uterus to contract to its pre-pregnant size. These contractions are experienced as afterpains, especially in multiparous women whose uterine muscles may have less tone.Choice C rationaleWhile some medications administered after birth can have side effects, severe cramps or afterpains are primarily a physiological response to uterine involution and the hormonal changes associated with breastfeeding, rather than a direct adverse effect of medication.Choice D rationaleHealing of the abdominal incision after a C-section causes incisional pain, which is distinct from the cramping sensation of afterpains. Afterpains are specifically due to uterine contractions, not the healing process of the abdominal wall.