if you are told you are 18 weeks pregnant...

[jorange5]

...how long have you actually been pregnant for? I mean, when was conception? Was it 18 weeks ago? Or 16?

My friend is confused. She found out she is pregnant and went for a scan and they said she is 18 weeks pregnant but do they estimate it like the doc does from LMP or from conception????? There is more than one possible dad so it's important.

16 weeks actually pregnant.

Unless they said the baby looked 18 weeks old? If they gave her a due date, and from that she is 18 weeks pregnant, she is actually 16 weeks pregnant.

it would mean sex 16weeks ago sorry so blunt!

They count from the first day of your last period to say how many weeks pregnant you are, even though conception occurs around two weeks after that(depending on when the middle of your cycle is. 28 days usual but if 40 days for example, then it would more likely to be about three weeks after last period). This calculation is not relevant when you speak to any doctor/midwife but it sounds like it will obviously make a difference to your friend.

A dating scan can also confirm age of baby but I am not sure if 18 weeks is too far along for this (the growth stages of baby are very specific early on so they can be quite exact about it, but then it varies more later, so dating becomes less accurate after a certain point).

18 weeks pregnant means a foetus is approximately 16 weeks old.. the first 14 days of pregnancy are the first half of your cycle, before you ovulate. based on a 28 day cycle obviously

12 weeks scan is usually more accurate in terms of dating

if the dates and her LMP match then it is accurate

Yeah, to be honest even a regular person can ovulate a little late etc. so I think the best way forward and the only accurate way would be a DNA when the baby is born.

It would be 16 weeks from conception assuming she ovulates around day 14. Lots of women don't. To be honest if she isn't sure who the father is then a paternity test is the only way to be certain.

Thanks all!

It looks like the father is not who she hoped it would be.