Which factors can contribute to fourth stage postpartum hemorrhage?

The factors that contribute to fourth stage postpartum hemorrhage are primarily related to physical complications following the delivery. Cervical or vaginal lacerations can disrupt normal healing and lead to significant bleeding if not properly managed. Additionally, a full bladder can prevent the uterus from contracting effectively, as an overly distended bladder can push the uterus upward and out of its optimal position, leading to poor uterine involution. Sequestered clots can also cause hemorrhage since if clots form and are not expelled, they can lead to retained products of conception or further bleeding.

Each of these physical complications directly affects the body's ability to manage postpartum bleeding effectively, making them critical factors to consider. In contrast, excessive maternal weight gain, inadequate prenatal care, and advanced maternal age, while potentially relevant to overall maternal health, do not have the same immediate mechanical impacts on postpartum hemorrhage. These factors might influence the risk of complications during pregnancy or labor but are less directly connected to the immediate causes of fourth stage postpartum hemorrhage compared to the anatomical and physiological issues highlighted in the correct answer.