Difference in EDD

Question

Hi fellow mummies, just went for my very first gynae appt a few days back, the gynae has roughly estimated for me to be at 6w4d with the ultrasound but based on the calculations from my 1st day of last period (I track religiously with an app) I should be somewhere 8w. That’s quite a gap :/ Not sure which one should I be following for me to keep track of my pregnancy progress? Can anyone help pls? #pleasehelp #firsttimemom

A. C. · Answer

I had my first scan at around week 6. Due to the size of the baby, my EDD was pushed back a couple of days, compared to what I calculated myself based on my last period. When I went for scan in week 8, my baby grow bigger hence it allows doctor to have a more accurate estimation of EDD. It was then brought forward a couple of days. My understanding is that the bigger the baby, the more accurate the EDD will be, as it is estimated based on the baby’s measurement.