Many measure from the pubic symphysis. The pubic symphysis is the place where the pubic bones meet in the middle-lower part of your abdomen. Measurements are made from the pubic symphysis to the top of the uterus. Your due date could be wrong, or there may be a concern about intrauterine-growth retardation or some other problem. Not every doctor measures the same way, and not every woman is the same size.
Babies vary in size.
Measurements differ among women and may be different for a woman from one pregnancy to another. If you see a doctor you don't normally see or if you see a new doctor, you'll probably measure differently. This does not indicate a problem or that someone is measuring incorrectly. It's just that everyone measures a little differently. Having the same person measure you on a regular basis can be very helpful in following the growth of your baby.