In assessing first trimester bleeding, which of the following is the most likely cause associated with pain and bleeding?

In the context of first trimester bleeding, the likelihood of experiencing both pain and bleeding points primarily to miscarriage. Miscarriage is the most common cause of bleeding in early pregnancy and is often accompanied by cramping or pelvic pain due to uterine contractions as the body expels fetal tissue.

Ectopic pregnancy could also present with pain and bleeding, but it typically involves more severe and localized pain, often on one side of the abdomen, and the clinical presentation may vary significantly based on the location of the ectopic implantation. While it is a serious condition, the symptoms can sometimes be more dramatic and acute than those typically associated with a miscarriage.

Placenta previa is more commonly associated with bleeding later in pregnancy, rather than in the first trimester. It involves the placenta improperly positioning over or near the cervix, leading to bleeding as the pregnancy progresses.

Hormonal imbalance could affect the menstrual cycle and lead to irregular bleeding, but it doesn't typically cause pain in the way that miscarriage or other pathological conditions do.

Given these factors, the association of pain with bleeding during the first trimester aligns most closely with the scenario of miscarriage, making it the correct answer.