when does a fetus have a heartbeat

A fetus starts to have a heartbeat at about 5 to 6 weeks of pregnancy. At around 5 weeks and 1 day gestation, the embryo’s heart starts beating with cardiac tissue beginning to contract. This early heartbeat can sometimes be detected using a vaginal ultrasound. The heartbeat is initially rapid and irregular, capable of pumping blood inside the vessels. By 6 weeks, the embryonic heartbeat is usually steady, around 110 beats per minute, and can be seen on an ultrasound. The heart itself is still developing during this period, starting as a fused tube and gradually forming loops, chambers, and valves over the next several weeks. By about the 10th week, the fetal heart is more fully developed, with formed aorta and pulmonary veins. A detectable "heartbeat" sound using a Doppler device typically comes after around 8 to 10 weeks. Essentially, the first heartbeat starts very early (around 5 weeks from the last menstrual period), but it is the cardiac activity or contractions rather than a fully formed heart. The heart continues to mature throughout the first trimester and beyond.