Hi ,my LMP was 15th August.I had an ultra sound on 21st dec and doc said your 18 weeks pregnant but my measurements shows I am 15.5 weeks pregnant. I had this gap since I am pregnant.doc also said there is no need to worry because you have a late conception.is there any thing dangerous or some problem with my baby.this is my third pregnancy .n measurements are according to 15.5 weeks.. *** answer

Stop worrying. Ultrasounds are notorious for not showing an exact size for the baby. As long as the baby is developing normally, there's nothing to worry about. Just as there are a wide variation of normal birth weights, there are variations of size at different stages of pregnancy.