when is the heart developed in a fetus
Heart development Heart development refers to the prenatal development of the human heart. This begins with the formation of two endocardial tubes which merge to form the tubular heart, also called the primitive heart tube, that loops and septates into the four chambers and paired arterial trunks that form the adult heart. The heart is the first functional organ in vertebrate embryos, and in the human, beats spontaneously by week 4 of development.[2]
Obstetric ultrasonography A gestational sac can be reliably seen on transvaginal ultrasound by 5 weeks' gestational age (approximately 3 weeks after ovulation).The embryo should be seen by the time the gestational sac measures 20 mm, about five-and-a-half weeks. The heartbeat is usually seen on transvaginal ultrasound by the time the embryo measures 5 mm, but may not be visible until the embryo reaches 7 mm, around 7 weeks' gestational age.[5][10][11] Coincidentally, most miscarriages also happen by 7 weeks' gestation. The rate of miscarriage, especially threatened miscarriage, drops significantly if normal heartbeat is detected.[12]