Babies can measure too big or too small, does that cause your lmp date to be off? or make it seem as if you're further along than you thought?

LMP date could cause: You may have recalled your last period date (lmp)incorrectly and then your due date may not be accurately calculated. You may have gestational diabetes and that can cause a fetus to grow larger more rapidly than it should. You may have decreased blood flow from the placenta to the fetus ( like from smoking) and this can decrease the rate of growth of the fetus.