Normal po ba na hindi marinig yung tibok ng baby during 16 weeks pregnancy?

san po ba? sa ultrasound na pineperform ni doc or via home doppler? if via home doppler, possible na hindi as per nagsell ng doppler sa shopee. kasi nagask muna ako before ako bumili nun. sabi nya yung iba as ewrly as 8 weeks. while yung iba at 16 and may iba na 20 weeks. pero kung sa clinic po yan, as early as 8 weeks kaya na po. if lagpas man, madetect na ni ob mo of may problem po