Hi,

I know anything is possible but how likely is it I was 44-46 pregnant when I gave birth, I put my last period around the 17th Nov 2011, and gave birth 23rd Sept 2012. I had three scans, one at 8 weeks, one at 13 weeks and one at 20 weeks. Nothing got mentioned about being further along then I was.

Are the measurements accurate when scanned? Especially on your dating scan?

Try this site for some good info and humor:
http://spacefem.com/pregnant/charts/duedate0.php

The reson I ask is because I'm in a long term relationship but slept with another guy around the 5th Nov 2011, I bled around the 17th but got told that could have been implantation bleeding, in that case my period before would have been roughly 21st Oct 2011. As pregnancy is counted from that date 21st Oct-23rd Sept is nearly 11 months and can't possibly be the other guys can it?

The reason I ask is because I'm in a long term relationship but slept with another guy around the 5th Nov 2011, I bled around the 17th but got told that could have been implantation bleeding, in that case my period before would have been roughly 21st Oct 2011. As pregnancy is counted from that date 21st Oct-23rd Sept is nearly 11 months and can't possibly be the other guys can it?

11/17 = 310 days = 44 weeks 2 days
11/5 = 322 days = 46 weeks
Not likely (don't count in months; they vary)
You can never really know, however, unless you do a DNA test. You might even be wrong about the dates you quoted. You don't even know if it was Nov 5, you say. And finally, you don't actually conceive on the date of LMP in 99.9% of cases; you conceive anywhere in the cycle, usually mid-month. It's all approximation.
Again - you will never know unless you test the child and either man.
You could explain this to your GYN and ask to go over the ultrasounds for clues, but it's still approximation.
Because you were overdue at 44 weeks, however, the probability that you conceived with the second man is higher than the earlier one.

I have a feeling that you didn't give birth even at 44 weeks 2 days. There would have been concern about this by 42 weeks, and talk of inducing. A baby can get too big for the cervix. They look quite different, usually. I would discuss ALL of this with your doctor before worrying about conceiving so long ago.

To answer the initial question. It is possible.

This is going to sound funny but, I know a girl who was 8 months pregnant and never knew it. Don't ask me how, even I still don't understand it. She went to the doctor with flu like symptoms, ended up finding out she's going to be giving birth in less than a month.

Cobra, here's the difference between the OP and your friend.

The OP knew she was pregnant, and she was under a doctors care. I have never ever heard of a doctor letting a patient go past 42 weeks gestation. There's a reason for this. Once you pass the 40 week mark, the climate in the uterus is no longer good. In other words, it's actually harmful for a baby to go past 40 weeks gestation.

Now, the reason that doctors will wait until 42 weeks is that conception dates are a guess, they can be off by 2 weeks before, or 2 weeks after. In other words, even though the woman thinks she's 42 weeks along, it's likely that she's only at 40, which is still safe for baby. Every day past the 40 week mark can put the baby at risk.

With my son I was 3 days overdue. At a mere 3 days my doctor had me going for non stress tests, and was talking about induction. So I learned a lot about why doctors are concerned when a women goes past the 40 week mark. I went for the non stress test, was told to come in the following Monday to be induced, but thankfully went into labor on my own the same day as the stress test on a Friday.

It's unheard of for a doctor to let a woman go to 44 weeks gestation, much less 46. It wouldn't happen.

Sounds like the OP is hoping that she was in fact 46 weeks pregnant, so that she can claim the father of this child. But it doesn't ring true. It's highly unlikely.

Time to do a DNA test.

Yep. I suspect that the bleeding 'around the 17th' was actually mid-month spotting (you didn't write down the previous period, and aren't even sure about the 17th). So is it possible that you had another period about 2 weeks later, around the first of Dec? That would put the count at 296, or 42 weeks 2 days. Even if you didn't have another period then, you more likely got pregnant just before then.

I've done some digging and now know 100% that I slept the other guy on or before the 5th Nov. I definatley bled for 4 days on the 18th Nov to the 22nd. I can't be sure on my period before that or if I bled after, but after reading conception can occur up to a week after intercourse and taking that into account it still would have meant I was 46 weeks pregnant when giving birth. After 3 scans I find it unlikely no-one would have noticed this?

No, it's not possible. The placenta has a life of about 42 weeks. Once it passes that it begins to deteriorate and will no longer have the ability to feed the fetus the necessary oxygen in order to survive.