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 and so appears as a 7 week baby? Please help.
Pregnancy scans and dates - can they be wrong??
- Thread starter Bradjeff
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Hate to be the bearer of bad news but it’d be extremely unlikely it’s yours if the last time you had sex was September. Scans are the most accurate way of confirming how far a pregnancy is & if she’s only 6/7 weeks & your 100% sure you haven’t slept together since September the baby won’t be yours. Babies don’t develop slowly & get out behind by 7 weeks. That’d be impossible. Sounds like she’s had 1 or 2 cycles (periods) since sleeping with you & fallen pregnant with the other man in November..
Thank you for your reply. 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?
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I agree with linnet here, if she is around 7 weeks pregnant now and you’s last slept together in September I’m afraid the baby is not going to be yours, internal scans are much more accurate then abdominal scans in the early stages, that’s because the baby is still absolutely tiny and the internal scan gets much closer to it to get more accurate measurements, the measurements they take can be slightly out, but only really by a week or so at the most, the baby can be developing behind slightly too, but only really by a week or so at the most
The 2 week add on thing can be confusing, basically how it works is women usually ovulate around 2 weeks after their period, then get their next period 2 weeks after ovulation, conception occurs around the time of ovulation, when your period is due but doesn’t come you are about 2 weeks pregnant then, but doctors and midwives date the pregnancy from the date of your last period so date you as being 4 weeks pregnant, women with pcos may not ovulate 2 weeks after period, for some women it can be months after period, but the next period is always due 10-14 days after ovulation, for women with pcos it’s often not accurate to use date of last period, need to use scan dates or date of ovulation instead to date pregnancy, but generally speaking if she around 7 weeks pregnant now she conceived around 5 weeks ago, so sometime in the last week of November, sperm can live up to 5 days in the female reproductive system though waiting for an egg to be released so the date of conception is flexible by a week or so.
The 2 week add on thing can be confusing, basically how it works is women usually ovulate around 2 weeks after their period, then get their next period 2 weeks after ovulation, conception occurs around the time of ovulation, when your period is due but doesn’t come you are about 2 weeks pregnant then, but doctors and midwives date the pregnancy from the date of your last period so date you as being 4 weeks pregnant, women with pcos may not ovulate 2 weeks after period, for some women it can be months after period, but the next period is always due 10-14 days after ovulation, for women with pcos it’s often not accurate to use date of last period, need to use scan dates or date of ovulation instead to date pregnancy, but generally speaking if she around 7 weeks pregnant now she conceived around 5 weeks ago, so sometime in the last week of November, sperm can live up to 5 days in the female reproductive system though waiting for an egg to be released so the date of conception is flexible by a week or so.
Has she been given an EDD (estimated due date) yet ? If she has I’d just google “when did I conceive?” Put the EDD into the online calculator & it should give you a rough date as to when she conceived but as Owl said it should show as being around 5 weeks ago. 2 weeks always gets added on as the dates go from last period rather than conception date. In all honesty I don’t really get that myself, probably why so many babies are born later than on time ! But yes it’s more than likely the babies the person she slept with in November which is unfortunate on yourself by the sounds of it.
Thank you for your replies. It has cleared it up a little for me. She’s not been given an EDD as of yet but how would that be determined? Her scans were done at the hospital as they wanted to check how far along she was due to her PCOS. She’s not yet seen her GP/Midwife but I’m guessing they’ll calculate EDD based off how far along she is? Which would mean sometime next August? Would there be any possibility it could be dated from Sept which would make an EDD of June? I feel like there’s just too much of a difference and it appears there’s significant differences between a 7 week embryo and a foetus at 13/14 weeks?
Brad I’m 15 weeks pregnant on Wednesday, due 26th June. Last period was 25th Sep & I conceived between 2-6th Oct so I know from where I am in my pregnancy that if her scans are showing she’s 6/7 weeks there’s no way she’s going to be due around the same time as me. She didn’t conceive until November...
Hi All,
So I have an update and am even more confused and now stressed than ever.
After the above dates issues my mind was somewhat put at ease and I accepted the fact that biologically the child could not be mine.
I now have further information which has confused the whole situation.
A second scan was had on 14th Feb which dated the baby at 14.3 days, again following on from the first and making it unlikely to be mine.
She went for her second trimester scan yesterday 28th March, she found out the gender and all other checks at this scan done. According to previous dates that should have put her at 20.3, however looking at their scan picture it states her as being 29 weeks 1 day.
How is this possible? That changes everything my two months and loves the dates back to when we last slept together. I have no idea what to think about all this at the minute again now. Has the tech just dated it wrong? Is such a change in dates possible? Has the baby had a growth spurt or were the first two scans wrong??
Please help!
So I have an update and am even more confused and now stressed than ever.
After the above dates issues my mind was somewhat put at ease and I accepted the fact that biologically the child could not be mine.
I now have further information which has confused the whole situation.
A second scan was had on 14th Feb which dated the baby at 14.3 days, again following on from the first and making it unlikely to be mine.
She went for her second trimester scan yesterday 28th March, she found out the gender and all other checks at this scan done. According to previous dates that should have put her at 20.3, however looking at their scan picture it states her as being 29 weeks 1 day.
How is this possible? That changes everything my two months and loves the dates back to when we last slept together. I have no idea what to think about all this at the minute again now. Has the tech just dated it wrong? Is such a change in dates possible? Has the baby had a growth spurt or were the first two scans wrong??
Please help!
The most accurate time to calculate the conception and due date are the 12 week scan. Up to this point all babies grow roughly the same. After this point they can differ but that seems like a huge jump to experience. Have they suggested why or done anything about it? I think they would need to investigate because certain conditions can cause baby to gain weight too quickly (gestational diabetes for example) but they can be managed. Still, that's a huge amount for the scan to change. So I would really push for another scan or at least an explanation of why the dates have changed so much. Had they given her a due date at the 12 week scan and have they changed to now?
I'm assuming this is on the NHS so if they really won't do anything about it can you get a private scan as a 2nd opinion? It may be that you have to wait until after the birth to do a DNA test as that will be the only way to know for sure.
I'm assuming this is on the NHS so if they really won't do anything about it can you get a private scan as a 2nd opinion? It may be that you have to wait until after the birth to do a DNA test as that will be the only way to know for sure.
Thanks for your reply. I wasn’t at the scan but she has called me and also sent me a picture of the scan clearly showing the date.
I should also point out that it wasn’t her who noticed the date it was her sister and the was after the scan had taken place. All she said to me was that the midwife just asked during the scan what her expected due date was which she gave as August as had previsouly been told. I have told her need to call the hospital and ask/query this and will be booking in for a second private scan if necessary. I’m just so confused at the minute.
I understand that at the start they all grow the same which is why we all accepted the dates and who the father is, could it be that the baby is just very big it’s showing as for in advance? She herself isn’t very big.
Marvellous_mum
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Do the scans show the gestational age on the scan? I just looked at mine and none of mine show a gestational age because as the ladies have said growth ranges. Maybe my PCT is different to others tho. If it does show it I would be questioning it as that's a very very big jump.
Marvellous_mum
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Also a 20 week scan and 29 week scan will look very different. At 29 weeks you'd struggle to get a full photo as baby would be too big. Alot of growth scans are done at 28 weeks for growth reasons.
I'd have thought 28 weeks would also be very difficult to do the checks because of the view not being as clear.
It's all abit strange
I'd have thought 28 weeks would also be very difficult to do the checks because of the view not being as clear.
It's all abit strange
Thank you for your replies.
I’ve had another look at the scan and on the scan it also shows the LMP as 6th September and then below that the age of 29w1. I have no idea where the sonographer got this LMP date from but could it be that she’s just randomly used that date - that would tie up with the gestation shown of 29 weeks.
Is the baby scanned and dated at each scan? Or was it her scan at 12 weeks which is the official date? This was her 20 week scan so I’m not sure other than checking the gender what more is officially done?
I’ve had another look at the scan and on the scan it also shows the LMP as 6th September and then below that the age of 29w1. I have no idea where the sonographer got this LMP date from but could it be that she’s just randomly used that date - that would tie up with the gestation shown of 29 weeks.
Is the baby scanned and dated at each scan? Or was it her scan at 12 weeks which is the official date? This was her 20 week scan so I’m not sure other than checking the gender what more is officially done?
Marvellous_mum
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A 20 week scan isn't for gender. A hospital has no legal obligation to tell you the gender. A 20 week scan is to check the anatomy of the baby, the heart, brain, vital organs. They only date a baby at 12 week scan. The sonographer would have to have been given that date, otherwise it's a random date to pick.
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I personally think she has given the sonographer that date as the LMP date and it’s automatically generated that particular gestational age, I’ve had a scan done at a place where they work like that - the computer generates a gestational age based on your LMP but then the sonographer tells you how far along you actually are based on the fetal measurements not the LMP
It’s all very strange and there’s no way she’s just jumped ahead that much in terms of est due date now, the est due date won’t change after the 12 week scan
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Brad, can't you just ask her for a private scan with just the two of you? At least then the sonographer will be able to tell you how far along she really is. It appears as though she really wants you to be the father but don't get forced into fatherhood. It wouldn't be fair on you or the real father.
