Anatomy CVS Embryology de8b1c7a Hea begins to beat in the week: A 4 B 5 C 6 D 7 High-Yield Explanation Hea beat begins by day 22 post-ovulation and can be detected by Doppler ultrasound. It is week 4 post-ovulation (or feilization) and 6 weeks from LMP (Last Menstrual Period).