Is pregnancy calculated from the start of the last menstrual period?

Patient's question:

No

Doctor's answer:

The normal gestation period for humans is approximately 40 weeks. In medicine, the first day of the last menstrual period is often used as the starting point for calculating the estimated due date. So, you are currently 105 days pregnant. Under normal development, it is usually possible to see the fetal bud and cardiovascular pulsation around 7 to 8 weeks of pregnancy. In normal intrauterine pregnancies, it is often possible to clearly observe the intrauterine gestational sac and the fetal bud with a heartbeat at 42 days after the menstrual period.