When does a fetus develop a heart beat?

Answer 1

• At 18 days [when the mother is only four days late for her first menstrual period], and by 21 days it is pumping, through a closed circulatory system, blood whose type is different from that of the mother. J.M. Tanner, G. R. Taylor, and the Editors of Time-Life Books, Growth, New York: Life Science Library, 1965, p.
• With an ultrasound, at about 3 or 4 weeks. With the device the doctor uses in the room, at about 9 weeks. I don't know for the things you buy at the store.
• I am going to disagree with this last answer. With a vaginal ultra sound a heartbeat can be detected as early as 6 weeks gestation but more commonly by 7-8 weeks gestation. Of course she could be right and we are just counting the weeks differently.
• With my first child my Dr. could hear my son's heart beat at 7 weeks with out a ultra sound and now being pregnant with my second child and having the experience in a medical setting working in a OB practice I have heard my baby's heart beat at 5 weeks and 3 days.
• Mayo Clinic says the heart begins to beat at 5 weeks and may be seen with an ultrasound.
• But note that the Mayo Clinic, numbers the weeks according to the start of the last period, so that conception is regarded as happening in week 2; thus the heartbeat begins during the 4th week after conception.)