Final answer:
The severity of afterpains on postpartum day 2 is increased by Multiple gestation (C) because it causes more stretching of the uterus, leading to stronger contractions during involution.
Step-by-step explanation:
The condition that would increase the severity of afterpains, or painful contractions, on postpartum day 2 is C) Multiple gestation.
Afterpains occur due to the uterus contracting as it returns to its pre-pregnancy size, a process known as involution. Conditions that overstretch the uterus, such as a multiple gestation pregnancy, can lead to more intense contractions as the uterus works harder to contract and shrink back to its normal size. In contrast, bottle-feeding can sometimes reduce the frequency of afterpains because it does not stimulate the production of oxytocin as breastfeeding does, which is a hormone that causes the uterus to contract. Diabetes does not have a direct effect on the severity of afterpains, while women who have given birth for the first time (primiparity) are generally likely to have less intense afterpains than women who have had multiple pregnancies.