When does cardiac activity typically appear during pregnancy?

Cardiac activity is typically first detectable via ultrasound around 6 weeks of gestation. At this stage, the developing embryo has formed significant structures, including the heart, which begins to beat in a coordinated manner. The ability to visualize fetal cardiac activity at this time is crucial for assessing the viability of the pregnancy. This is often confirmed during a transvaginal ultrasound when the embryo is large enough and the heart structures are sufficiently developed for detection.

Options that suggest earlier weeks, such as 4 or 5 weeks, may be prior to the expected development of the heart to the point where it can be visualized or detected. By 7 weeks, cardiac activity can definitely be confirmed, but the typical point of detection that is most reliable and universally accepted in practice and studies is around 6 weeks, making it the most accurate answer.