How do you date an IVF pregnancy?

[Silver45]

Just that really! Is it from LMP? Do you take Egg collection into account? Thank you.

Egg collection should be treated as day 14 of your cycle, whether it was or not as the calculations by lmp are based on a cycle of 28 days with ov in day 14. Some drs do struggle with this though. My gp couldn't get at all that he should use egg collection date rather than lmp or transfer date.

Fresh cycle? If so then take the EC date, go backwards 14 days and that would be the equivalent of LMP when calculating due date.

Oh really? That's interesting....

I'm 4 more days pregnant than I thought then...

Can I ask- do MWs know this?!

Fresh cycle - from egg collection. Google IVF due date calculators.

When I went for my midwife booking in she just trusted the due date I gave her.

If your MW knows it's an IVF pregnancy, she should just ask the due date your clinic gave you.

This is what's confusing me- my clinic do 14 days from embryo transfer!

ivf.ca/duedate.php

This is the calculator I used and it matched up with the EDD the clinic gave me

My midwives went by the EDD the clinic gave, at our 12 week scan we were measuring 5 days ahead and the midwife wanted to change our EDD until she saw it was an IVF pregnancy and said she couldn't because there was no doubt how old baby was. At later scans he was measuring spot on for our 'IVF dates' but arrived at 36+2 so had a mind of his own anyway

That seems odd. Non IVF dating assumes a 28 day cycle and ovulation on day 14. So as Eurochick says, you would count EC as day 14, to create a dating methodology that aligns to these standards. Can't think why they'd do it differently? Surely it's just going to cause confusion over sizes/dating scans/inductions. It might even mean the NT test can't be performed, due to dating issues. I would get back in touch with the clinic to ask them why they do it that way.

Thank you so much all. So glad I asked this. Changes things by 5 days I've just found out- a lot!