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Childbirth/Ultrasound accuracy

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Question
Lmp 5/27/12 due date 3/3/13...Which ultrasound is more accurate? A 8 week ultrasound or a 13 week ultrasound? Also I had an ultrasound at 32 weeks the baby was measuring 34 weeks and about 5 lbs the doctor says im having a big baby. He will send me for another ultrasound at 38 weeks.. Will I deliver earlier since baby is big?

Answer
An 8-10 week transvaginal (not abdominal) ultrasound is the most accurate, to within +/- 1 day.  The size of a baby does not correlate to when it will be born.  It should be allowed to come when it's ready.  Ultrasound at 32 weeks can be off by 2 weeks in either direction and up to 2 pounds either direction in weight. So, these measurements cannot be used to confirm a large baby because they can be so very wrong.  The only way to actually determine whether a baby is large is by performing consistent measurements weekly over the course of the pregnancy to establish a true growth rate.

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Catherine Beier MS CBE

Expertise

I can provide evidence-based information and current research findings concerning childbirth and pregnancy. My specializations include natural childbirth, pregnancy and birth interventions, fetal positioning, labor induction, choosing a care provider, midwives, homebirth, unassisted birth, natural pain relief, medications in pregnancy and birth, informed consent, understanding the risks and benefits of childbirth choices, doulas, waterbirth, childbirth methods, childbirth education classes, cesarean section, and VBAC.

Experience

I have been a childbirth educator, mother, author, public speaker, researcher, and birth advocate for the past 9 years. I am also the author of GivingBirthNaturally.com, a site dedicated to natural childbirth and pregnancy information. I publish evidence-based articles on pregnancy, childbirth, newborn care, and post-partum care. I'm also a mother of three children, two daughters and one son all born naturally.

Publications
My book, Birth Outside the Box, was published in 2007.

Education/Credentials
I hold a Master's degree in communication disorders with an emphasis in child development. I am also an independent childbirth educator.

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