LMP/Ultrasound Accuracy

[lilbjayce1130]

Ok, I have a sticky situation and I'm super embarrassed about it. I've been with a man over a year and a half, we were off and on during February and March. I slept with a man on Feb 17 and March 17, but between Feb 20-March 15 I was with my bf. I am now 30 weeks pregnant, due 11/29. When I slept with the man on Feb 17th I took extra birth control (as an "emergency contraceptive"....stupid I know) and had my period that started around the 20th. (which coincides with my period in january and my pretty regular 28 day cycle) According to fertility charts, etc. it says I would've been fertile from the 2nd-10th of March. I just want to ensure that March 17th isn't the daddy to my baby. I have spoke with my doctor and a gestational specialist and they both say it's very unlikely, but I forgot to mention that I took the emergency contraceptive on the 18th of March (again) and didn't start to bleed or get my period, which would be my first skipped period....and which indicates to me that I was already pregnant. On my 20 week ultrasound the numbers completely matched with my LMP and my doc stated that conception was probably around the 8th of March, but I feel like it was a bit earlier, like the 2nd. Am I ok trusting this and believing my bf is the father to my baby as my LMP and u/s dates match? Ugh, I know this is wordy and lengthy. thank you people.

[annie2186]

I think with you taking emergency contraception - which CAN mess up your cycles - and not monitoring your fertility..........it would be hard to tell.....

I do think that it is more likely that you got pregnant the times you DID not take PlanB the next day (with your bf?).

I wonder if you remember when you took a pregnancy test? Did you get a positive close to when you first missed your period? If that is the case, it is almost certain that you got pregnant earlier.

For example - it usually takes about 10-12 days past ovulation that you would get a FAINT positive.

So if you can tell me when you tested and how dark the TEST line was - I might be able to help you more

[MaerynPearl]

I would say from the info you gave that you are one of the few whose ultrasound is pretty much spot on. (I would actually put ovulation around March 6th, which DTD on March 2nd can make you pregnant when you ovulated on March 6th, but DTD Feb 17th most certainly could not have)

[WifeofAnt]

You're slightly more preganant than me, about a week off, which means you ovulated earlier than me by about a week. I ovulated March 14th. There's no way in heck even I could have gotten pregnant on the 17th so (as long as you're really as far along as you say) I am 100% sure you did not conceive on March 17th or February 17th.

[lilbjayce1130]

Thanks ladies so much. I took pregnancy test on March 29th and it was CLEAR as day, it wasn't faint at all. As far as being 30 weeks, I would assume that's right, as that's what the doc says (and what she said the U/S said....) and going by what I think was my LMP (20th of Feb), and I'm measuring and have been been measuring to this date pretty exact. Gosh I hate being in this predicament but I love knowing that there's support/forums like this. Thanks for all your input......

[lilbjayce1130]

AWifeofAnt, so you think I am safe to assume I didn't conceive on March 17th?

[WifeofAnt]

About Feb 20th you got a period, right? You'd be expecting another period (you said they were 28 days) around March 19th. If you didn't ovulate late you would have ovulated somewhere between the 3rd and the 9th, much too early to get pregnant the 17th.
Even IF you ovulated late on the 17th you would be due December 8th, over a week later than your current due date. A 20 week ultrasound *could* technically be that far off but the other factors including your regular 28 day cycles, the fact that you got a solid positive only 12 days after the 17th, and that your other measurements are coming back are all coming back in agreement make me think its pretty safe to assume you were already pregnant on March 17th. (And possibly pregnant enough to get a faint positive on a sensitive test too!)