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How To Calculate The Date Of Conception Based On Menstrual Cycle?
Question: I had my ultrasound done on July 3, Saying 8 week 1 day old. My first date of my last menstrual period is April 24, 2015. I am at a 35 day cycle
1) does the 8 week 1 day old per ultrasound meaning "gestational age" or " fetal age"?
I think it represented fetal age as if it is from the gestational age, I would be 10 weeks while fetal age is at 8 weeks. Am I corrected?
2) per my blood test did on XXXXXXX 9, I was told that I was at my 4th week. So my doc was very confirmed that I must have conceived in the week of May 10-16.
3) with the above info, what would be by due date and conception date?
1) does the 8 week 1 day old per ultrasound meaning "gestational age" or " fetal age"?
I think it represented fetal age as if it is from the gestational age, I would be 10 weeks while fetal age is at 8 weeks. Am I corrected?
2) per my blood test did on XXXXXXX 9, I was told that I was at my 4th week. So my doc was very confirmed that I must have conceived in the week of May 10-16.
3) with the above info, what would be by due date and conception date?
Brief Answer:
31st January is the delivery date
Detailed Answer:
Hello dear, good to talk to you again.
I understand your concern and anxiety related to the issue.
The ultrasound always gives gestational age and has a difference of 10-14 days with the age calculated by last menstrual period because of inherent calculation discrepancy.
It is because of the fact that even a fraction of a millimeter calculation accounts for a few days of gestational age.
So even if 3 ultrasounds are done on same day there will be a difference of few days between each of them.
Also fetal position at the time of calculation matters a lot and thus an attitude of flexion will give less age compared to that of extension.
Your doctor is right in deriving the date of conception around 10-17 may which coincites with ovulation.
So all factors viz your 35 day cycle, ultrasound calculation and bHCG levels if put together then final date of conception was around 10-17 may and calculation from 24th April makes your delivery date to 31st January.
So I hope you are satisfied with the reply but in case you have any questions about it, I will be glad to answer.
Regards
Dr Manisha
31st January is the delivery date
Detailed Answer:
Hello dear, good to talk to you again.
I understand your concern and anxiety related to the issue.
The ultrasound always gives gestational age and has a difference of 10-14 days with the age calculated by last menstrual period because of inherent calculation discrepancy.
It is because of the fact that even a fraction of a millimeter calculation accounts for a few days of gestational age.
So even if 3 ultrasounds are done on same day there will be a difference of few days between each of them.
Also fetal position at the time of calculation matters a lot and thus an attitude of flexion will give less age compared to that of extension.
Your doctor is right in deriving the date of conception around 10-17 may which coincites with ovulation.
So all factors viz your 35 day cycle, ultrasound calculation and bHCG levels if put together then final date of conception was around 10-17 may and calculation from 24th April makes your delivery date to 31st January.
So I hope you are satisfied with the reply but in case you have any questions about it, I will be glad to answer.
Regards
Dr Manisha
Above answer was peer-reviewed by :
Dr. Vinay Bhardwaj
Answered by
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