Which observation at 10 weeks gestation could most likely confirm a woman's pregnancy?

A positive pregnancy test is an effective way to confirm a woman's pregnancy, particularly at 10 weeks of gestation. This test detects the presence of the hormone human chorionic gonadotropin (hCG) in urine or blood, which is produced shortly after a fertilized egg attaches to the uterine lining. By 10 weeks, hCG levels are significantly elevated, making this test highly reliable.

While a missed menstrual period can suggest pregnancy, it is not definitive as various factors, such as stress or hormonal imbalances, could also cause amenorrhea. A positive ultrasound assessment and detection of a fetal heart rate can both indicate pregnancy but usually occur later in the first trimester. Therefore, a positive pregnancy test offers an early and confirmatory method of detecting pregnancy within the first 10 weeks.