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A member asked:
What week do fetuses stop growing at the same rate? when do genetics kick in, therefore causing ultrasounds to be less accurate?
2 doctors weighed in across 2 answers
Progressive: The earlier the ultrasound the more accurate the gestational age estimate. At 6 to 8 weeks the estimate is +/- 4 days, at 18 weeks it is +/- 10 days, buy about 30 weeks it is +/- 21 days. The growth of a fetus rapidly accelerates after about 28 to 30 weeks.
Answered 9/7/2013
4.9k views
After 1st trimester: First trimester us's are the most accurate compared with 2nd and 3rd for the reason you give, that fetus growth is much less affected by genetics or environmental factors in the 1st trimester.
Answered 9/7/2013
4.9k views
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