Monday, March 7, 2011

Relationship Between Baby's Birth Weight and Diabetes

This is part 3 in my Pregnancy and Birth Outcomes Analysis and continues to explore potential relationships of fetal macrosomia.



Comparing Average Fetal Weights for Women With Diabetes, Gestational Diabetes and No Diabetes


Conclusion


 It seems that either women who have gestational diabetes are doing a great job controlling it, or that gestational diabetes does not affect baby birth weight by that much.  However having diabetes pre-pregnancy does seem to influence the baby's birth weight quite a bit more. 


    Results:


    • There was an approximate 1.5oz difference in weight between babies whose mothers had GD versus those whose mother's did not have diabetes.
    • There was an approximate 4.6oz difference in weight between babies whose mothers had diabetes before they got pregnant versus those whose mother's did not have diabetes.
    • There was an approximate 3.2oz difference in weight between babies whose mothers had GD versus babies whose mother's had diabetes before they got pregnant.
    • The confidence intervals do not overlap so the differences are statistically significant.



    Method:

    See here to see information about the data.
    • I used sql server to calculate an average baby weights for women who's baby's were full-term (37 weeks or later and were put in the following groups
      • Had diabetes before they got pregnant (did not distinguish between Type 1 or Type 2)
      • Diagnosed with Gestational Diabetes
      • Did not have diabetes
    • The confidence intervals were calculated in the same manner as this post.


      1 comment:

      Lauren @ Hobo Mama said...

      This is so interesting, once again! I've heard GD described as a made-up disease, so it's intriguing to see that it doesn't affect birth weight as much as people say or think it does. I can see how non-gestational diabetics, with a long-term history of blood sugar control problems, could have a harder time keeping blood sugar stable during pregnancy and would therefore be more likely to have problems like macrosomia. But if GD's really just identifying normal fluctuations in blood sugar in pregnancy, it would make sense that many women with GD would actually not be at any risk for a larger baby. Maybe only those whose GD was the first indicator of a larger blood sugar problem would.

      Well, that's just speculation — thank you for the data!

      I've been wondering about macrosomia's stated complications. One thing I read a lot is "increased risk of C-sections." I can't help but wonder how many of those C-sections are due to actual shoulder dystocia and the like (various emergency situations due to the baby truly not fitting through the birth canal), and how many are due to ultrasounds suggesting possible macrosomia and then doctors saying, "Just in case, let's have a C-section." Because that's not a real risk, then, but one induced by the medical establishment.

      Anyway, thank you for another fascinating analysis!