Hello, I’m pregnant Based on my lmp

Ask The Doctor > Questions & Answers > Hello, I’m pregnant Based on my lmp

Patient: Hello, I’m pregnant. Based on my lmp I should be 21 weeks I did an ultrasound today and in the report it says the age is 22 weeks. I’m confused

Doctor: Thank you for writing to us.In fetuses, the LMP and the Ultasound dates always vary by a little bit. The LMP dating is calculated by taking the last known period date till the present date.The ultrasound calculates the size of the fetus. Based on the size, the fetuses age can be decided. Usually, there is a slight difference and this can be from 2 to 4 weeks. Since the difference only varies by 1 week, you need not worry.To allay your fears, please talk to a Gynecologist if needed. All the best.

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Dr. Jimmy Obaji M.D.

Dr. Jimmy Obaji completed his residency in Family Medicine at the University of Manitoba. He currently operates a walk-in-clinic in downtown Toronto.

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