Due date

[HM]

I've just been for my 20 week scan and my due date has been put back by 2 weeks due to the size of the baby. 

Can anyone explain to me how this can happen?  All the calculations have been done from the date of my last period, and my symptons have pretty much tied it with where I should be based on me now being 20 weeks, ie morning sickness starting at 5-6 weeks, starting to feel the baby kick a couple of weeks ago.  I will call my midwife tonight/tomorrow to let her know but just wondered if anyone could explain this to me?  I've done an internet search but not had any joy - just keep finding websites that tell me my baby is due on 18th Feb based on the dates of my last period.

Any ideas welcome.

thanks

[OBonio]

It's not an exact science but going by size is more accurate than when your last period was. If the baby measures more than 10 days either side of your EDD, they will change the EDD.

Our baby measured 6 days bigger than the EDD, and she was 7 days early.

If you think about it, you only become suspicious of being pregnant based on when you miss your period. So the fertilisation could have been at any time 4 weeks prior to that, depending on your cycle. Unless you only had sex the once in those 4 weeks, in which case, you know the exact date of conception.

[spudqueen]

Personally I don't think it's an exact science. I remember my due date being moved back with my first baby because they measured the size of the babys head. I queried this at the time because I said that not everyone has the same size head so why should babies? In the event he was 6 weeks early (according to their calculations - 4 by mine) but was virtually the same weight as my second baby who was 4 weeks early, so I still think they got it wrong. I wouldn't worry too much as the baby will come when it's ready anyway!

[qapmoc]

Hi,   HM you are making the same mistake that lots of people who live all the time with technology and gadgets make,  your body and the new baby are NOT machines where the date x formula = exact answer, but a natural system with things that vary from person to person, so stop worrying about it and enjoy.

HM this is no comment on you but you know I do worry sometimes how most modern people expect everything to be exact and perfect in a world where nature itself relies on the variations to progress.

[nicolab6]

Hi - this happened with both of my kids, and can be explained by the gap between periods.  I normally have periods once every 7-8 weeks, therefore my more fertile point is about week 4 from last period, not the normal week 2.

I agree with previous comments, relax, as long as baby is growing, they will come when they are ready.

BTW - Both of mine were planned C section due to breach presentation.  Whether they were 'old' enough or not, they were an OK size and healthy so that's all that matters.

[carla81]

I was told i would have an adverage size baby, his birth weight was 12lbs 2oz. my friend was told she was going to have a large baby and set her off 3 weeks early her birth weight was just over 5 lbs. Personally i don't think they can give an accurate measurment.

good luck anyways!