Good day ladies. Who has already had experience with childbirth and un…

Good day ladies. Who has already had experience with childbirth and understands how to calculate pregnancy term. I have an obstetric term now less than and give birth only on March 23rd. According to the ultrasound screening, the fetus and term is more and by March 14th already giving birth. This is two opinions of different doctors and who should believe? The menstrual cycle is stable but short was 20-25 days all, they say because of this too according to the screening it needs to be counted. But in our clinic everyone considers standardly as they know how.