Plz check the image show below

Every scan you do shows the gestational age of the baby and the due date changes accordingly. If you or your doctor have taken the LMP wrong by mistake then the scan will show how the baby is progressing. It is said that the earliest scan is the most accurate for confirming the due date. And 15 days plus/minus is taken as the margin but one month is never seen. And as far as your query is concerned the baby is delivered at 40 weeks i.e 4 X 10 weeks = 40 weeks or 10 months. So the doctor is right. You'll deliver in July, not June. Happy pregnancy!

Do u have irregularity in periods?