Gestational Diabetes & Baby Size: Understanding C-Section Risks & Recovery

Question
I have an identical twin sister who had gestational diabetes.  Her 2nd baby got stuck (he was 8 1/2 lbs) and had to be delivered via c-section.  My baby (also g.d.) is measuring 8 lbs right now at 37w3d (13.5 cm head circumference).  The doctor is going to do a final ultrasound next week to decide whether or not she wants to do a scheduled c-section.  She said she never forces g.d. moms to push too long or use instruments like forcepts, and she knows that recovering from BOTH a long labor and an emergency c-section is rough.  

Is it safe to assume that my twin sister and I have the same size pelvis and that my baby would likely get stuck at 8 1/2 lbs as well?  Should I opt for the scheduled c-section?  (Her first baby was 6.14 lbs and gave her a 2nd degree tear after 3 hours of pushing.)

Answer
Every pregnancy is different and the size of your pelvis may be slightly different that your sister's. ACOG recommends that we offer a cesarean section if the estimated fetal weight (EFW) of the baby is 9.5 lbs. You may be able to deliver an 8lb baby thorugh your pelvis while your sister could not. There is no way to predict it. I would see what the next sonogram shows and make sure to get an EFW. Then you can make your own decision. It is safer to have the cesarean that risk shoulder dystocia or the neurological damage that can  effect the baby if its shoulders get stuck. Recuperation from a cesarean is not so bad.