Pregnancy scan and conception date

[Bradjeff]

Hi, my ex partner has PCOS and very irregular periods. She went for a check up yesterday due to stomach pains and was told she was pregnant. She was then sent for a scan where she was initially told she was 6 weeks pregnant. The tech then did an internal scan and said she was actually 7w1d. We last slept together unprotected on 18th sept. She had some bleeding on sept 20th (not sure if this was period or implant bleeding and pain now). We then had protected sex on the 29th sept. That was the last time we slept together. She had since told me she slept with someone during November. How accurate are the scans especially as they changed by a week? Is it possible the baby could be mine even though it would then mean she would be 14 weeks pregnant? Is it possible for the weeks to be confused during the scan or for 14 week baby to be developing very slowly? Please help!

 

[Robynxo]

Hi there!
I don't hear much of slow growing babies, as I would think they would have been miscarried.

Internal scans are much more accurate for an early pregnancy, so that would be the reason the dates changed. There are some differences between 6 weeks and 7 weeks (tadpole stage of pregnancy), but there is a HUGE difference in baby at 7 weeks vs. 14 weeks, so it should be very safe to say she conceived in late November, a whole month after your last encounter with her.

I am no doctor, of course, but if you look up 14 week ultrasound and 7 week ultrasound, you would see they are vast differences and confusing them would be near impossible, especially by a trained technician.

 

[Chezzer]

Ouch kinda in the same boat I've done the same thing. Those scans are pretty accurate tbh the only way u will truly know is a DNA when the baby is born x

 

[Bradjeff]

Hi there!
I don't hear much of slow growing babies, as I would think they would have been miscarried.

Internal scans are much more accurate for an early pregnancy, so that would be the reason the dates changed. There are some differences between 6 weeks and 7 weeks (tadpole stage of pregnancy), but there is a HUGE difference in baby at 7 weeks vs. 14 weeks, so it should be very safe to say she conceived in late November, a whole month after your last encounter with her.

I am no doctor, of course, but if you look up 14 week ultrasound and 7 week ultrasound, you would see they are vast differences and confusing them would be near impossible, especially by a trained technician.

Thank you for your replies. I was thinking the same and tbh it’s not really what I wanted to hear. I was concerned as it changed over a week from the normal scan to internal scan. Is that normal?

She was initially sent for the scan as she was having some pains and when they did a urine check it showed up she was pregnant. She had no idea herself and hasn’t kept track of any dates of periods or ovulation etc. And it was at the scan that they dated how for along she is.

If they said she is 7w1d when did she likely conceive? I don’t understand the two week add on thing fullly especially as her periods are so irregular?

 

[bumble b]

She fell pregnant from sex on 25th november roughly. Hope this helps.

 

[Weebles]

According to the date you gave of 9/29 for being the last time you were intimate there really isn't a way that this current pregnancy is yours. Pregnancy is initially dated by the first day of her last cycle. This makes the assumption that ovulation occurred on cycle day 14. The dating scan can and often will be different from this because women don't all ovulate on day 14 and also, implantation can occur sooner or later than the average of 6 days which impacts crown to rump length which is what they base the dating scan on. Early on all pregnancies develop at a predictable and consistent rate so scans are quite accurate in dating. I believe the longest implantation can take is around 12 days. And the longest sperm can stay alive before ovulation is 7 days. So with that the latest she could have had a scan dating the baby at 7w1d (from the last time you had I tercourse) is around 12/6.

Now depending on the status of your relationship with her during November you may or may not be okay with sticking around. I was left by my oldest's father right after I found out I was pregnant. And I actually ended up dating, something I didn't think would happen but it did. Anyway, it might be uncommon but it's not unheard of. My husband has been the only real father my son has ever know.

 

[Bradjeff]

According to the date you gave of 9/29 for being the last time you were intimate there really isn't a way that this current pregnancy is yours. Pregnancy is initially dated by the first day of her last cycle. This makes the assumption that ovulation occurred on cycle day 14. The dating scan can and often will be different from this because women don't all ovulate on day 14 and also, implantation can occur sooner or later than the average of 6 days which impacts crown to rump length which is what they base the dating scan on. Early on all pregnancies develop at a predictable and consistent rate so scans are quite accurate in dating. I believe the longest implantation can take is around 12 days. And the longest sperm can stay alive before ovulation is 7 days. So with that the latest she could have had a scan dating the baby at 7w1d (from the last time you had I tercourse) is around 12/6.

Now depending on the status of your relationship with her during November you may or may not be okay with sticking around. I was left by my oldest's father right after I found out I was pregnant. And I actually ended up dating, something I didn't think would happen but it did. Anyway, it might be uncommon but it's not unheard of. My husband has been the only real father my son has ever know.

Thank you very much for providing a detailed response and showing dates so clearly. This whole situation has left me quite devastated if I’m totally honest. Even by your given dates of everything occurring at their last possible time points the scan she had two days ago would have made the baby 10 weeks and I think even that on scans would be too different compared to one at 7 weeks? Unless the growth was 3 weeks behind where it should be? (How possible is that as a scenario?).

 

[bumble b]

Thank you very much for providing a detailed response and showing dates so clearly. This whole situation has left me quite devastated if I’m totally honest. Even by your given dates of everything occurring at their last possible time points the scan she had two days ago would have made the baby 10 weeks and I think even that on scans would be too different compared to one at 7 weeks? Unless the growth was 3 weeks behind where it should be? (How possible is that as a scenario?).

It's very unlikely i'm sorry. There is a huge difference between 7 & 10 weeks x

 

[Weebles]

Growth that lags that far behind the latest possible point of conception and implantation is highly unlikely in a viable pregnancy. I don't think anyone wants to use the word impossible but it is highly unlikely. Really I think the only way the dates could be that far off is if the tech was totally incompetent and measured incorrectly. I just don't think it's realistic, especially since the most recent time you were intimate protection was used, making the timeframe from 9/29 even more implausible. It's a big stretch. (The reason for the difference between the internal scan vs the external scan is because when babies are so small they are easier to see and therefore more accurately measured with an internal ultrasound)

I understand that feeling of grasping for straws and I'm so sorry that this is leaving you feeling devastated, especially if your partner was unfaithful. It's a big hurt that's difficult to face. It's hard to accept and I'm sorry that these weren't the answers you were wishing for. I hope with the truth you are able to knowingly move forward in a direction of your choosing.

Also, it is worth mentioning that if you need difinitive proof beyond any measure of doubt there are prenatal paternity tests. But fair warning, they're quite pricey. Prenatal Paternity Test, Prenatal Paternity Testing, Prenatal Paternity Tests

 

[Kiwiberry]

I'm sorry but the other ladies here posting are completely correct. There is really no way that the baby is yours honey based on the dates and information you provided. Has she told her other partner about the pregnancy yet?

 

[justonemore31]

It would prob be the other guys due to how far along she is. If it was Sept she would already be in her 2nd trimester.

 

[Bevziibubble]

I think it's the other guys going by the dates you've given. I'm so sorry. The only way to know for sure is a DNA test