A nurse is caring for a client who is 5 hr postpartum following a vaginal birth of a newborn weighing 9 lb 6 oz. (4252 g). The nurse should recognize that this client is at risk for which of the following postpartum complications?

A. Retained placental fragments This is incorrect because retained placental fragments are more commonly associated with prolonged third-stage labor or incomplete placental expulsion, rather than fetal macrosomia. B. Uterine atony This is correct because a large baby (macrosomia) causes overdistension of the uterus, increasing the risk of uterine atony (failure of the uterus to contract effectively). This can lead to postpartum hemorrhage. C. Puerperal infection This is incorrect because puerperal infection is usually related to prolonged rupture of membranes, poor hygiene, or invasive procedures, rather than fetal size alone. D. Thrombophlebitis While pregnancy increases the risk of clot formation, the most immediate concern for this client is uterine atony and postpartum hemorrhage.