Is Early Ultrasound Accurate?


Dear Midwife,
I had a ultrasound 2 days ago and it said I was six weeks instead of ten weeks as I originally thought. I have irregular periods. How accurate is this result?

My first baby was diagnosed as not thriving in the womb at close to my 40-week mark and was induced because the ultrasound said my baby was only 3 pounds but she was born at delivery weighing at 6 pounds.

Please tell me, should I trust this or will I have to go through more testing to get an accurate due date?


A six-week ultrasound is almost always accurate, assuming that this is a viable pregnancy. If they were able to see a heartbeat (not always possible this early), that would be more confirmation that everything is ok.

The only way you could be ten weeks along and have this ultrasound is if you were about to miscarry.

Estimates of weight at term are notoriously off, as you have found out. Personally, I trust my hands much more than I trust an ultrasound.

Good luck with your pregnancy!
-- Cynthia, CNM

Cynthia Flynn

Cynthia Flynn, CNM. PhD, is the General Director of the Family Health and Birth Center which provides prenatal, birth, postnatal, gynecological and primary health care to underserved women and their families in Washington, D.C. Recently Cynthia served as Associate Professor of Nursing at Seattle University. There she not only taught, but remained in full scope clinical midwifery practice at Valley Medical Center where she cared for pregnant and birthing women, and practices well-woman gynecology, family planning, and treatment of sexually transmitted diseases.

Cynthia founded Columbia Women's Clinic and Birth Center, where she took care of pregnant women and infants up to two weeks of age and attended both birth center and hospital births. Before Cynthia earned her CNM, she worked as a registered nurse in labor and delivery and postpartum and is a certified Doula and Doula trainer.