The number they go with is an average of all the measurements they take. Some may be behind, some may be ahead, but the final number is what you want to look at. Our baby boy's head was measuring almost 3 weeks ahead most of my pregnancy, but slowed down closer to the end, and he had a regular sized melon at birth!

I had preeclampsia with my previous pregnancy and when I had my first ultrasound the baby was measuring about two weeks behind. A few weeks later I lost the baby, so of course with this pregnancy I worry a lot about the baby. I lost my first baby at 21 weeks and I am now 19 + 3 with my second. I went for my first ultrasound with this baby at 18 + 4. It was nice to hear that the blood circulation and placenta looked normal. The baby was measuring at 18 + 2 so that also put my mind a bit at ease. When I looked at all of the measurements I saw that some measures were farther ahead ex: 19 + 2 while other measurements were behind ex: 16 + 6. Is it normal to have some measurements behind? It makes me nervous and since I haven't had many ultrasounds I'm not sure if this is normal or not. My doctors haven't seen the results yet but will in about two weeks. If anyone could chime in with their thoughts that'd be great.