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Childbirth/Early ultrasounds

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Expert: - 10/26/2009


Question
I was just wondering, how accurate are early transvaginal ultrasounds? Does it matter if you do not know your LMP and can tell give you a pretty good estimate of when you may have gotten pregnant? Thank you.

Answer
Carmen,


Early transvaginal ultrasounds between 8-10 weeks are the most accurate, within +/- 3 days.  In most cases, they are accurate within +/- 1 day.  It does not matter if you do not know your LMP, although it can be helpful to determine if the growth rate is appropriate.


For example, if by your LMP you should be 10 weeks, but the ultrasound shows 5 weeks, then there may be a problem with the pregnancy.  If you are supposed to be 10 weeks by LMP but are 13 weeks via ultrasound, then again, there could be a problem or you could have had implantation bleeding, not a true period.


In any case, a fairly reliable estimate of conception will also be determined, which is usually about 2 weeks less than the weeks you are pregnant (If you are told you're 10 weeks, 1 day, then you most likely conceived 8 weeks, 1 day ago).



Best,
Catherine

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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 Giving Birth Naturally, 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. To learn more about what normal birth looks like, view the natural childbirth video of my son being born at home unassisted.

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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