Pregnancy dating based on conception
This free online conception calculator will determine the conception date -- including the day of the week -- based on the selected month, day, and year of your pregnancy due date.
This is because the fetus is growing so quickly that there is a big difference in size from week to week.
So if you have questions related to any of those fields, please seek out the advice or counsel of a qualified physician or attorney.
Most dating scans are done with a trans-abdominal transducer and a fullish bladder.
Ultrasound examinations from 12 to 22 weeks are regarded as being within 10 days of accuracy (or up to 10 days earlier or 10 days later than the woman's calculated due date).
Ultrasounds performed after 22 weeks gestation cannot be used to estimate the due date of the baby because the size no longer reflects the age very well.) the fetus is clearly seen on trans-vaginal ultrasound and the heart beat can be seen at this early stage (90 to 110 beats per minute under 6 to 7 weeks, then 110 to 200 beats per minute as the baby matures).