A baby's heartbeat starts very early in pregnancy, typically around 5 to 6 weeks of gestation. The heart begins as a simple tube and starts rhythmic contractions as early as 5 weeks, with cardiac activity detectable by ultrasound around 6 weeks. By this time, the heart is just beginning to pump blood, and while it may not always be audible yet, the heartbeat can often be seen as a flickering or pulsing on an ultrasound.
The heartbeat develops a more regular rhythm by about 5 weeks, and more fully formed fetal cardiac activity is usually detectable by ultrasound between 6 and 7 weeks of pregnancy. Around 10 to 12 weeks, the heartbeat may be audible with a Doppler device.
In summary, the baby's heartbeat starts at about 5 to 6 weeks of pregnancy, marking a critical early milestone in fetal development.
