How to count the weeks of pregnancy after IVF

Hello ladies, I’m an egg donor recipient and I found out I’m pregnant a few weeks ago… but actually I don’t know how to count the weeks of pregnancy after IVF. My fertility clinic says I’m 7 weeks pregnant, but my gyn says 6… who’s right?

My last period was on Oct 5, the eggs were retrieved from the donor on Oct 19, and the embryo transfer was on Oct 22. So… How do I count the weeks of pregnancy now? I got my first ultrasound scan next week and I’m worried not to know exactly my gestational age or due date… as pregnancy is very different from week to week. Thank you!

Dear karma,

In a natural pregnancy, the gestational age is calculated based on the date of the last menstrual period (LMP) because there’s no possible way that we can find out the day in which egg fertilization took place.

In IVF pregnancies, we can know accurately the precise embryo development stage at which fertilization occurs (1 day after egg retrieval). In your case, this happened on the 22nd of October.

The weeks of pregnancy in IVF are counted from the day of the transfer, and the estimated due date is calculated by adding 38 weeks to the day of egg retrieval.

I hope this helps,

Best

My nurse at clinic explained this just the way you did. Even not knowing the thing earlier I tended to think it starts from the day of ET. I believe ivf pregnancy differs from a natural in many ways. I think you get more obsessed with your ivf pregancy. You try to keep all the things under the control as you’ve made this long trip to get your bean inside. You take it all more emotionally, as for me. I don’t insist though, but this difference is vivid to me.