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Dr. C.
Dr. C., Board Certified
Category: OB GYN
Satisfied Customers: 3064
Experience:  30 yrs experience, awarding winning educator
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Need second opinion!! (Dr owen please) Slept with a ex on

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Need second opinion!! (Dr owen please)
Slept with a ex on 10th march and got back with partner straight after had bleed 31st march (light) continued regular sex with partner ON may 5th found out pregnant 15th may had 6week 3 day scan due date jan 5th then 9 weeks and 13 weeks all agree due date 5th jan how accurate is transabdominal scan? is this pregnancy from march 10th so worried? I no sperm can live for a week pls help?
Hi, It's Dr. C. Board certified Ob-gyne. I can help you today. It's impossible that this pregnancy was from sex on March 10th. There is ZERO chance. When the ultrasound shows 6 weeks and 3 days, it is in "gestational age". This counts from the last expected period. Actually the pregnancy was just 4 weeks and 3 days along pn May 15th. So if you count back, you'll see it's impossible. The longest sperm has been reported to live is 7 days. The error on an ultrasound is 3 days back. So the absolutely earliest sex that could have produced this pregnancy is April 4th. This is WAY absolute in terms of telling us that there is NO WAY POSSIBLE that this pregnancy is from sex on March 10th. So relax and let that go. Please reply if I can explain better or add details.
Customer: replied 2 years ago.
Thank you is the fact that the earliest conception date April 4th cause of the abdominal scan used instead of vaginal?
And would you say conception was 15th April? My last bleed was 31st march just not sure if it was implantation or a real period I'm guessing if it was not a period the ultrasound would of picked that up am I correct?
And thank you I will let it rest.
The reason for the April 4th is because the ultrasound has an error rate of 3 days plus sperm can live up to 7 days. So I added 10 days to the most likely conception date. My estimate for most likely conception date is April 14th. That is obviously very close to the 15th. The last bleed being March 31st matches all of this information. I'm 100% certain that you did not get pregnant from sex on March 10th. It's impossible. Please reply if I can clarify anything else.
Customer: replied 2 years ago.
Thank u dr I think I had it wrong thinking due to me having a transabdominal scan that's why it would be off few days and if I had a vaginal scan it would of Been much more accurate.
As these were all abdominal. I guess I can rest assured this pregnancy is not from march.
Thank you again
Yes I agree. With the abdominal, the measurements might be a few more days off but still there is ZERO chance of that great of an error. I do think you can rest assured 100% that this pregnancy is not from March 10th. Anything else I can help with today?
Customer: replied 2 years ago.
Is it possible to no the error rate on transabdominal scans? So I add that plus 7 days (sperm) for overall inaccuracy? My pics were pretty clear but heartbeat was seen at 9 weeks on scan at 6 weeks only sacs
For an abdominal scan, we can say even up to a 7 day error and still it will not impact the answer. If we said 7 days error for abdominal, it would bring the earliest conception date down to March 31st. This is a LONG way off from March 10th. It's simply IMPOSSIBLE that this pregnancy is from sex on March 10th. Even if we use a 7 day error plus a 7 day sperm life. Usually sperm can only live 3-5 days. But even if we use the greatest possible errors, it's still 2-3 weeks off from March 10th. There is ZERO CHANCE this pregnancy is from sex on March 10th. It's not possible. I hope you can give this worry a rest now. Please reply if I can clarify anything else.
Dr. C. and other OB GYN Specialists are ready to help you
Customer: replied 2 years ago.
Thank you I will rest now.
You're welcome. I really hope you do. We get this type of question quite often on this website. Sometimes the timing is very tight and paternity testing is needed. But with your information I can truly say 100%. It's not even close. Good luck with the rest of the pregnancy.
Customer: replied 2 years ago.
Hi Dr I had my fundal height measured and I am measuring 37cm at 34 weeks will this have any impact on the gestational age or conception date.
Or can I still relax about this... I was spot on fundal height until 34 weeks now I'm measuring 3 weeks more due date supposed to be jan 5th/6th from early u/s it's just measuring 3 weeks would probably take me to march 10 conception?
This doesn't change anything, as I previously clarified. Towards the end of pregnancy, the fundal height is impacted by genetics, amount of fluid, how the baby is sitting etc. While all babies are the same size up until about 12 weeks, after that, they start growing at increasingly different rates due to various factors. This is why not all babies weight 7 pounds 7 ounces at 40 weeks gestational age. Some weight 5 pounds and others 10. This doesn't change my answer at all. The most accurate way to tell conception date is by ultrasound done during the first trimester of pregnancy. Your baby will be here soon so it would be good if you could let go of that worry in the face of such strong evidence of correct conception date.
I have reassured you as much as I can at this point.
Customer: replied 2 years ago.