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When's the best time to get pregnant? Use our interactive ovulation calculator to work out when you're most fertile and most likely to conceive.

Please can anyone help sort this out? Can you conceive during a period?

(18 Posts)
SledsImOn Sun 16-Dec-12 20:15:48

I'm getting towards the end of this pregnancy and am starting to worry about dates, and when I'm actually due as it's never been very clear.

The scan I had supposedly at 12/13 weeks went a bit wrong as the baby was too big - they put me at 14+3 - 14+5 going on measurements. Which was about 10 days off from LMP dates. This puts conception at day 2-4 of my last period.

I was charting when I conceived. I had no positive OPKs, no temp rise, apart from day 10 and day 13 of the following cycle, and around day 14 of the previous one.

I tested negative from approx day 15 of this following cycle until about day 27 when I got a positive pregnancy test. (obsessive POAS-er!)

Also when I was having my last period, I hadn't had sex for around 8-10 days (can check chart but that's what I remember when I looked when I was first pg) though I think I had sex on day 5 of period/cycle.

The thing is, both my 20 week and my 34 week scans (growth scan) have confirmed he's exactly on course for the dates they gave me, at the 12(14) week one. Or I would think it was just a blip.

So from what I can figure out, my dates are right and I conceived when I thought I ovulated (day 11/14 of second cycle) and also, their dates are right as the baby is keeping to what they said at 12 week scan.

Could I have had a delayed or second ovulation from the previous cycle, and still have had a period? (I was on antibiotics and painkillers for about 10 days)

Any thoughts? What's going on - and am I due in 3 weeks, or 5, or last week?!! smile (might be looking at induction, so would be useful to know)

MolotovCocktail Sun 16-Dec-12 20:34:54

I'd go with the hospital dates because what you're otherwise describing is very confusing! You've had 3 scans now that date you at the same place, so I'd go with them. It is possible to ovulate twice in the same month. Although it is more likely to conceive during your fertile window, it is possible to get pregnant at any point in the month. Your antibiotics might have affected your cycle.

With my DD2, te hospital dated me a one week ahead of what I knew I was. So, I was dated as being 13 weeks instead of 12 at the dating scan. Now, I was taking Clomid so I knew when I'd be ovulating. I know the 1-2 days we conceived her. I needed to have an ELCS for her birth and she was booked in for THEIR dates of 39+3. She was only 6lb 9oz (DD1 born naturally at 40+2 and was 7lb 5oz). So if DD2 had gone to 40 weeks, she would have been roughly her sister's size. No way was she 39 weeks.

But there are so many variables with your case that it's difficult to be convinced by your dates. And, in complete honesty, I'd only be worrying if you were going to have an ELCS.

How far along are you?

SledsImOn Sun 16-Dec-12 20:43:47

oh thankyou for replying and for taking the trouble to try and understand my post!

I'm supposedly 37 weeks tomorrow. By my own dates, (usually have short cycles) and my chart and my temps etc, I'm only about 35 + 4, because I think I conceived on about day 11-14 of my cycle. They put it at day 2-4.

I have low fluid so they are talking about induction, possibly - and I know that depends on the dates, by theirs I'm 'term' tomorrow but by mine I'm way off.

Also have been having some false/pre-labour contractions, (irritable uterus apparently) and really want to have this baby at home, like last time, and that depends on gestation as well.

So all a bit of a nightmare...the best outcome would be ds arriving sometime in the next couple of weeks, I guess, but I'll still never knowwhat date he was made! I wish babies had a factory time printed on their necks smile

Thanks again

bonzo77 Sun 16-Dec-12 20:49:00

I'd go with the hospital dates, especially as they've been consistent and your history/ chart is a bit confusing. FWIW if they're worried about low fluid I'd want to be in hospital. I had this and DS2 spent 8 days in NiCU and SCBU as he had problems breathing and there were concerns over his feeding, both related to poor placental function, which probably caused the low fluids.

SledsImOn Sun 16-Dec-12 20:52:55

Oh crikey...sorry to hear that sad

The thing is if they are right it means I conceived during a normal period, having not had sex for over a week, and not having any other signs of ovulation at that point.

could implantation have an effect on dates? My brain is going round in circles!

Re the fluids, I've had a growth scan which showed the baby is fine, growing well, doppler on cord was great etc so feel very fortunate it just seems to be that the fluid is leaking slightly. I'm having another scan on Tues so if it;s dropped any lower, they will send me to consultant.

MolotovCocktail Mon 17-Dec-12 09:57:15

Implantation takes place around 3-7 days after 'successful' intercourse (!) but this is taken into account already so I don't think it'd have any effect on your dates.

As for fluid levels being low: wouldn't an earlier birth day be better in that case? I'm not experienced with this aspect of antenatal health, so don't quote me here! In any case, babies are usually able to cope quite well outside of the womb after 36 weeks; with each weekly increment, the cases of 'wet lung' and other respiratory issues drop a lot. I'm convinced I was only just about 38 weeks when my little squagde was born and she <touches wood> was fine.

I'd discuss this with your CMW and consultant (if you see one) because it will just play on your mind otherwise.

Best of luck xx

MolotovCocktail Mon 17-Dec-12 10:00:43

Btw, I raised the issue with my OB whilst the CS was being booked and he assured me that the hospital dates are more accurate, and that I'd had te senior sonograper do my 12/13 week scan.

Whilst I accepted what he said, I wasn't 100% convinced. I found out that even if she was born at 38+3, statistics were on her side, so I decided to go with the birth date. If I hadn't been sure, I wouldn't have agreed to the CS on that day.

MolotovCocktail Mon 17-Dec-12 10:02:46

In a long-winded way, in saying that I understand your quandary. Whilst I think that your hospital is correct, I would be mothering myself silly if my thoughts were to the contrary x

MolotovCocktail Mon 17-Dec-12 10:03:23

'mythering' not 'mothering' turns autocorrect off phone!

wanderingalbatross Mon 17-Dec-12 10:21:13

I have had the opposite, both times I've not been as far on as I thought by a couple of weeks (I have long cycles). I don't see how I conceived later than I thought as all the symptoms and dates lined up with my guess. But each scan the sonographers have known immediately, before taking measurements, how far along I was. They see loads of scans and are very good at estimating age. And having seen the massive differences from the various early scans I've had, I can believe that the sonographers can tell the difference between different weeks gestation. So I am left thinking that dating conception isn't as cut and dried as is suggested!

SledsImOn Mon 17-Dec-12 11:17:02

thankyou both so much smile

Molotov, I get what you mean, and I'm glad your little one was fine - I think I'll have to get used to just never knowing when this one was conceived! It's kind of impossible, well I thought it was, that their dates could be right but then again - well, he was huge on the scan, we both looked at the screen and went 'wow that's a big 12 week baby!' before she took any measurements.

Wandering, I think you're probably right and they see so many that they do 'know' - but I just wonder how on earth he managed to be conceived at that point in a cycle.

Oh having some more leaking and it's turned pink so MW wants me to be seen, in case I'm going into labour...but 37 weeks now so should be Ok.

Thanks again thanks

MurderOfProse Mon 17-Dec-12 11:36:19

Going against the grain here, but if you were charting your dates are the right ones. You can conceive on your period, if you ovulate really early and the sperm are particularly hardy (5-7 days has been reported) but I don't think this happened here. I trust a woman who charts and knows her body over a doctor and their "textbooks" any day of the week. If I trusted in doctors 100% I would not have two of my DC right now (long story..) - it is always good to question.

I make big babies. I also chart and POAS obsessively. All my children have measured at least a week ahead by around 12 weeks (not by much at all 8/9 weeks and spot on or even a day behind at 6 weeks) If you'd had a dating scan before around 10 weeks it's not unreasonable to go by those dates because they're +/- 5 days. Embryo growth is pretty uniform up to about 10 weeks. But then all bets are off and babies start exhibiting variances in growth depending on who they ultimately are, plus a few other factors like the quality of the placenta etc. My first two babies were born 98th percentile, my third was 50th BUT there were possibly issues with the placenta.

I went with the hospital dates for my first which put DD 3 days behind. At 37w2d by my dates (BFP at 8dpo) I went into labour. By their dates I was 36w6d, a few hours short of the cut off date for the homebirth I wanted, so I was sent into hospital. The panic involved in that (it was a precipitous labour) and the incompetence of the midwife at the hospital left me with short term and long term issues. And that was over a 3 day discrepancy. Admittedly this was bad luck but who knows what might happen in the future and now I lie to them over my LMP just so my dates are right by ovulation.

If you're ten days out and you're going into labour now, that is too early and they might not realise they should be preparing for a premature baby. I would highly recommend you tell the midwife your concerns, and explain that the dates are based on a scan done post 10 weeks when growth patterns are less consistent. Hopefully you'll get a reasonable one!!

Good luck!

SledsImOn Mon 17-Dec-12 13:10:47

Wow, thankyou for such an excellent post. Very reassuring - and I've just been monitored and inspected in all sorts of ways, at the hospital up the road, and I'm not in labour - so that takes the pressure off! smile

Looking back it does seem to suggest there is a +/- 7 day accuracy with the 12ish week scan - which could mean that the baby is just really big, maybe 98th or something as you say yours were. And that would put me back at 35+ something.

I think the issue might arise again if the baby is actually late, which tbh I can't imagine right now as another 4/5 weeks of this is not a good thought grin but if they decided to induce at what they thought was 41 weeks, and I was really only 39+3, that might cause problems.

I'll have to go back and look at the dates again I think and make sure I know when I think I conceived. I still have the FF chart I think online somewhere, from those 2/3 cycles.

Thanks again for your help. It is good to know I might be right, it certainly makes more sense than their dates in all ways but scan measurements.

SledsImOn Mon 17-Dec-12 13:18:21

[url=]My Ovulation Chart[/url]

I don't know if this will work but it's supposed to be a link to my chart if you're interested.

MurderOfProse Mon 17-Dec-12 13:56:32

I'm on FF too smile

I would eat my hat if you didn't ovulate on day 13 from that chart, I really would.

Weirdly with my "big" babies, they all slowly slid down the percentiles over the years to find their true heights and weights which are below average - ironically the bigger they were at birth (percentile-wise) the smaller they've ended up, my second went from 98th to 12th by the time she was 24 months! With the exception of me and my brother and father, everyone else on both sides is either short or very short so this doesn't surprise me. I guess there's not much relationship between weight at birth and weight in a few years. Perhaps you just have a very excitable placenta that provides super nutrition! Or you ate very well.. believe me, I eat well in pregnancy blush 4 stone of well.

Yes, right now I think you're probably fine (other than the risks associated with an earlier birth if you went into labour right now, but often at this stage when baby is ready, baby is ready if you see what I mean - DD1 was fit as a fiddle at 37w2d) As you say, it's the pressure for induction that's the big one. I really hope you don't get that far so it's just never an issue!

SledsImOn Mon 17-Dec-12 14:42:25

Oh thankyou....that is brilliant, to hear you say that. I thought I must be going mad! They have me conceiving on day 2-4, it's bonkers, it's just so unlikely.

Well in that case I'm going to adjust (mentally) my own dates to around 20th January...and see who's right grin

I did eat well in the first tri - I had awful morning sickness/verging on HG, apparently and was on super strong meds for it which meant I could put on, rather than lose weight this time (3rd pg - lost loads of weight the other two times) and I ate constantly to try and counteract the feeling empty/feeling sick thing. So maybe that is it.

I'm glad if children adjust though...thinking about it ds1 was 6lb9, and is now very chunky, he was like Buddha by 3 months on just breastmilk...and ds2 was 8lb12 and is teeny now!

Thanks for all your help...I'll let you know!

MurderOfProse Mon 17-Dec-12 19:38:09

Lots of luck, and I hope you get a sympathetic midwife! Not all of them don't listen, but it's luck of the draw really as I'm sure you know. Perhaps it simply is that you had all the pies and baby ate them!

Forgot to mention - my mum says she conceived my brother whilst on her period with a condom (she calls him her immaculate conception!) so it is possible, but having seen your chart no way no how, especially if you had negative OPKs either side of the positive ones. Plus your temps clearly show ovulation too.

Then again a big baby is more likely to thrive if they're born early so it's not the end of the world if stuff happens soon. DD2 was born at 35w5d and was almost 7lbs. Apgars of 10 and 10 and that was with an EMCS! She came home with me from the hospital, no special care.

Hope all goes well!! Sending you "decent midwife" vibes ;-)

SledsImOn Mon 17-Dec-12 19:40:27've really helped and it's much appreciated smile

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