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Dr. C.
Dr. C., Board Certified
Category: OB GYN
Satisfied Customers: 3064
Experience:  30 years of experience and an award-winning educator.
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June 23 I found out I was expecting. On July 22 I had an

Customer Question

June 23 I found out I was expecting. On July 22 I had an ultrasound done at the hospital. Uterus measures 10.4 x 6.7 x 7.3cm. Within the uterus is a gestational sac with fetal pole and yolk sac. Mean sac size is 3.4cm. Crown rump length is 1.7cm. Saying
gestational age was (8 weeks 5 days). Another ultrasound done on July 30 said 9 weeks 2 days. This one on the 30th was less than 4 minutes long and just to get a quick estimate of how far along I was by obgyn office. When was my conception? My period happened
around May 20. I know I was off before May 27th. How do you come up with conception??
Submitted: 1 year ago.
Category: OB GYN
Expert:  Dr. C. replied 1 year ago.

Hi, Thanks for asking for me. I can help you with this.

To come up with best conception range, the ultrasound done between 7 and 10 weeks of gestational age is most accurate.

You had one done on July 22nd at gestational age 8 weeks 5 days. Using that measurement, the most likely day of conception is July 5th with a range of July 2nd to July 8th. Because sperm can easily live for 3-5 days, sex as early as June 27th could have resulted in this pregnant. Rare reports of sperm living as long as 7 days so if we consider that, it could be from sex as early as June 25th.

So sex from June 25 to July 8th could have resulted in this pregnancy. The further away from that range the sex you're worried about is, the less likely that's the father. What days are you worried about? Depending on how far away from that range, we can say 100% or not.

Customer: replied 1 year ago.
My last menstrual cycle started May 20 (I believe) and I was off before May 27th.
I went to hospital July 22 and they did the first ultrasound saying I was 8 weeks 5 days. So I was trying to figure out conception from then?I hope before June 11 was when I concieved.
Customer: replied 1 year ago.
I just got confused with saying July 5th since I found out July 22 by vaginal ultrasound I was 8 weeks 5 days. And they did all kinds of measureme ts.
Expert:  Dr. C. replied 1 year ago.

Sorry I made a big mistake and meant June all along instead wrote July. I was distracted and apologize.

Expert:  Dr. C. replied 1 year ago.

Ok, you wrote some wrong dates too!! We were both off. So let's start over.

Customer: replied 1 year ago.
Lol. Okay give me a second to re-type it all.
Expert:  Dr. C. replied 1 year ago.

Let's be clear.

You had an ultrasound July 22nd showing 8 weeks 5 days. So most likely conception date is JUNE 5th with a range of JUNE 2nd to JUNE 8th as being most likely.

Expert:  Dr. C. replied 1 year ago.

When was the dangerous sex you don't want?

Expert:  Dr. C. replied 1 year ago.

If it was after June 11th you're good.

Customer: replied 1 year ago.
On June 19th I took a clearblue advance pregnancy test and it said positive 1-2 weeks estimated. So June 23rd it was confirmed that I was expecting by health department test. On July 22nd I had a transvaginal ultrasound done at the hospital. Uterus measures 10.4 x 6.7 x 7.3cm. Within the uterus is a gestational sac with fetal pole and yolk sac. Mean sac size is 3.4cm. Crown rump length is 1.7cm. Saying gestational age was (8 weeks 5 days).
Another ultrasound done on July 30 said 9 weeks 2 days. This one on the 30th was less than 4 minutes long and just to get a quick estimate of how far along I was by obgyn office.
When was my conception? My period happened around May 20. I know I was off before May 27th. How do you come up with conception??
Expert:  Dr. C. replied 1 year ago.

Really the biggest error possible with an ultrasound done during the 8th gestational week is 5 days. So June 10th is really the latest possible conception date.

Customer: replied 1 year ago.
I had messed around on the night of June 11, morning of June 12. We used the encare spermicide but no condom. I just want to make sure this is my partners baby.
Expert:  Dr. C. replied 1 year ago.

How regular are your cycles? From the 1st day of one to the 1st day of the next, is it 28 days?

Expert:  Dr. C. replied 1 year ago.

This timing is really tight. I don't think I can say 100% unfortunately. The 2nd ultrasound pushes the conception even closer to the 11th-12th. I think you'll need paternity testing. It's just too tight to be 100% sure with just the ultrasounds and last period to go by. The paternity testing can be done with your blood and a swab from one of the guys.

Customer: replied 1 year ago.
My cycles are 28-29 days.
Here is my periods I have recorded
DEC 25TH*
JAN 22
FEB 21*
MARCH 23 *
APRIL 21
MAY 20
The ones without stars I didn't have logged but believe those are correct dates or I may be a day or two off
Customer: replied 1 year ago.
Do I have to wait until the baby is born to do a paternity test? Anyway to do it discreetly?
Expert:  Dr. C. replied 1 year ago.

No need to wait. Yes it can be done discretely with the cooperation of just one of the men. Go to the website of the state you live in and put "paternity testing" in their search engine. You should be able to find info about reputable labs that do such testing. It will require just a blood draw from you and a swab from the cheek or blood draw from just one of the men. Perhaps the man from June 11-12 will be willing?

Any other questions?

Customer: replied 1 year ago.
Not sure if it helps but hcg quantitative test was done on July 22nd and it's range was 170161
Expert:  Dr. C. replied 1 year ago.

The HCG doesn't help. The range is too wide. The ultrasound is the most accurate. And it's showing that the timing is really too tight to be able to say 100%. I'm sorry about that. But in this situation paternity testing will be needed. Anything else I can help with? I wish it was clearer.

Customer: replied 1 year ago.
How wide open is conception dates? Like how many days am I fertile to concieve
Expert:  Dr. C. replied 1 year ago.

If no more questions, please leave a rating for my service. I aim for excellent and appreciate your feedback.

Expert:  Dr. C. replied 1 year ago.

Sorry I didn't see that follow-up question until now because we both posted at the exact same time.

The egg lives for 24-48 hours but sperm can live for 3-5 days with rare reports of up to 7 days. So the range of possible sex days that can result in pregnancy is usually around 3-5 days but can be as long as 7 days.

Anything else?