"..at
six weeks of pregnancy, an ultrasound can detect "a little flutter in the area that will become the future heart of the baby," said Dr. Saima Aftab, medical director of the Fetal Care Center at Nicklaus Children's Hospital in Miami. This flutter happens because the group of cells that will become the future "pacemaker" of the heart gain the capacity to fire electrical signals, she said."
"if doctors put a stethoscope up to a woman's belly this early on in her pregnancy, they would not hear a
heartbeat"
What exactly do we mean when we talk about a "fetal heartbeat" at six weeks of pregnancy?
www.livescience.com
"The flickering that we're seeing on the ultrasound that early in the development of the pregnancy is actually electrical activity, and the sound that you 'hear' is actually manufactured by the ultrasound machine." Dr. Verma added.
Dr. Jennifer Kerns, an OB-GYN and associate professor at the University of California, San Francisco, also told NPR that this noise is simply not a sign of a working heart or functional cardiovascular system.
The term is used colloquially to describe the start of a cardiovascular system forming - but it isn't a heartbeat, according to experts
www.businessinsider.com