Muscle strain or uterine cramping: This is likely due to the physical trauma from the fall, which can cause uterine cramping or muscle strain in the abdominal or pelvic area, especially in early pregnancy when the uterus is still in the pelvis.

Placental abruption: Although there's no bleeding mentioned, placental abruption can sometimes present with pain before any visible bleeding occurs. It's a condition where the placenta separates from the uterus, which can be triggered by trauma.
Uterine contractions: These could be caused by the fall and might not necessarily lead to immediate bleeding. They could be a response to the trauma, potentially leading to preterm labor if the pregnancy is far enough along.

Ectopic pregnancy with rupture: Although the patient is in early pregnancy and there's no mention of bleeding, a ruptured ectopic pregnancy is a life-threatening condition that requires immediate attention. The fall could potentially cause a rupture if an ectopic pregnancy was present.
Uterine rupture: In cases of previous uterine surgery (like a C-section), a fall could potentially cause a uterine rupture, which is a medical emergency.

Ovarian torsion: This is a rare condition where the ovary twists around its ligaments, cutting off blood supply. It can cause severe pain and is more likely in pregnant women due to the displacement of pelvic organs. However, it's less directly related to a fall and uterine pain.
Hemorrhage into a corpus luteum cyst: This could potentially cause pain and might be related to the fall, though it's less common and would likely be associated with some form of bleeding or more specific symptoms.