Originally published in November 2021; last updated August 2025. There is a functional, beating heart in every human being by 6 weeks of gestation[1] The heart is the embryo’s first functioning organ, which starts to develop as early as 16 days after fertilization.[2] The first heartbeat occurs approximately day 22-23 after fertilization, which is 5 […] The post The Science Behind Embryonic Heartbeats – A Fact Sheet appeared first on Lozier Institute.
