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How accurate are conception dates

A 29-year-old female asked:
Dr. Ryan Phasouk
Family Medicine 19 years experience
Accurate: Dates of delivery are in general very accurate. Given a normal pregnancy and and an accurate history of the last menstrual period, it would be safe t... Read More

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A 28-year-old female asked:
Dr. Yvette Kratzberg
Pediatrics 25 years experience
Fairly accurate : Evidence suggests that ultrasounds more accurately predict your due date than using your last menstrual period—but only in the first trimester and ear... Read More
A 23-year-old female asked:
Dr. Gerard Honore
Fertility Medicine 30 years experience
Not a percentage: First trimester us is usually considered to be accurate within a week, or +/- 3-4 days. There is no percentage implied, it doesn't work like that. In... Read More
A 23-year-old female asked:
Dr. Robert Kwok
Pediatrics 34 years experience
Accurate in a range: Ultrasound pregnancy dating gives a date and a range. The date is an estimate. That means the date is not a single point in time. So, when an ultrasou... Read More
A 22-year-old female asked:
Dr. Jane Van Dis
Obstetrics and Gynecology 19 years experience
11/14/13: Based on the information you provided, the 'average' date of conception would be appx 11/14/13. While 11/25 could be the conception date, it's highly... Read More
A 30-year-old male asked:
Dr. Gurmukh Singh
Pathology 50 years experience
Depends. You may not know the exact date of conception. It also depends on how you define conception. If you feel conception is the time on which the ... Read More
A 29-year-old female asked:
Dr. Piotr Obara
Radiology 15 years experience
Yes: Ultrasound dating is most accurate early in the pregnancy using the crown-rump length (crl) of the small fetus. The measurement can be done starting ... Read More
A 20-year-old female asked:
Dr. Gerard Honore
Fertility Medicine 30 years experience
Depends: A 1st trimester ultrasound, if done correctly, will date you within one week of conception.
A 23-year-old female asked:
Dr. Robert Killian
General Practice 29 years experience
Conception: Only you can answer this question. Only you know when your last menstrual period was. You can confirm nearly every single piece of information about ... Read More
A 27-year-old female asked:
Dr. Lori Semel
Pediatrics 36 years experience
Dating: If you are 15 weeks and had four ultrasounds, I would say the dates are pretty accurate.
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