At 8 weeks of pregnancy, what does it mean to be small for dates? Obstetrical Nurse Wanda F Steele has some information to help address this concern.
Wanda F Steele, RN

Your question
This is my first pregnancy, and I had my first prenatal visit yesterday. During my pelvic exam, my nurse midwife informed me that my uterus is smaller than it should be at 8 weeks, based on my LMP. She did not seem concerned and I followed her lead until I got home and started thinking about it. I have an ultrasound scheduled in 2 weeks but now I am worried and don't want to wait that long. Other than the possibility that I am not as far along as indicated by my LMP, what could be the other causes? - Amanda

The expert answers
Dear Amanda,

First off, don't jump to any conclusions. It is difficult to gauge an increase in the size of the uterus when it is still as small as it is at 8 weeks. The midwife was comparing it to "average," and the obvious conclusion is that you may not be as far along as you thought. Just because your period occurred at a certain date does not mean that you ovulated exactly as expected. This would mean that you could be less, or in other cases, farther, along that expected.

The other reason for a uterus not to be growing as expected is because the pregnancy is not progressing normally and will probably end in a miscarriage. (Miscarriage happens in an estimated 20-25% of all pregnancies.)

Ultrasounds offer their best predictive value as far as size and dates when they are done between 8-10 weeks of pregnancy. There is a blood test (quantative beta hCG) that can be done -- the second one 48 hours after the first -- that can give some reassurance, but no guarantee, of an progressing pregnancy.

I think your midwife would have ordred these tests if she had any real indication of a problem. As long as you have no cramping or bleeding, then go to your ultrasound with the expectations of seeing that little baby in there with that tiny little heart just beating away.

Good luck to you.

Wanda :)

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