Got my dates wrong!

[ALickyBoomBoomDown]

Hey all,

Just a bit confused and was wondering if you could put my mind at ease a bit! First timer here!

So basically the first day of my last period was Boxing Day last year - it lasted for four days. I took a pregnancy test in early February using the Clear Blue digital one and it said I was 2-3 weeks. Booked midwife appointment, she worked out that I would be due 2nd October and that I would be 12+1 today. We went for our first scan yesterday and immediately the lady doing the scan said that we were definitely not 12 weeks and it was more like 9.5-10 weeks. Long story short, I have to have another loss of blood tests done next week and another scan the week after.

Is this quite a common thing to happen? Do I literally just add two weeks onto my first due date?

Thanks!

There are probably people out there who can answer this better than me, but like you my midwife at our booking in appt at 8 weeks originally told us we were 1 week ahead of what the 12 week scan said. They gave us a new due date at the 12 week scan which was based on the measurements they took then. I guess it’s because no one actually knows for sure when you ovulated so the period dates are just a guess until they can do actual measurements and give you a more accurate estimation. Good luck in the rest of your pregnancy! 🙂 xx

Do you have a regular cycle? Is it a bit longer than the assumed 28 ish days? You could ovulate a little bit later than the norm. All of these things can have an impact on when you conceived and therefore your due date. LMP is the best way for midwives to estimate due date before you have a dating scan between 11-14 weeks. You will get a new due date (edd) at your next scan and that will be the one you will use going forward. Congratulations.

That's great to know. Thank you both! I have had a few periods that have been a bit off the usual mark since having my implant removed a couple of years ago. Hopefully the next scan will make us feel a bit more solid!

Yes this happens sometimes, like pp have said, the due date based on your last LMP is only used until confirmed by your 12 week scan and then they change your due date based on fetal measurements, which is much more accurate. Now you say you've had some funny cycles, it sounds pretty likely that you ovulated later than your MW would have estimated from your LMP and are not quite as far along as she thought.

The difference between 9/10 weeks and 12 weeks is awesome! You'll be amazed at how much the baby has grown and developed in those couple of weeks. I've loved having scans every two weeks and 12 weeks after the 10 week one was my favourite!

Interestingly, I have known of people with IVF pregnancies (ie absolute certainty of when the egg was fertilised) have their dates changed at 12 weeks and have perfectly healthy pregnancies matching the 12 week scan date. My expected IVF baby consistently measured one week ahead (retained my due date) until she settled down bang on perfect for dates around 16 weeks, where she remains at 27 weeks! Just goes to show how variable it can be!

In my first pregnancy, my dates put me further on than I was. My cycles were long and irregular. I was given my 12 week scan when I knew I wasn’t that far, I was only 10 weeks so had to go back as it was too early for the nuchal test.

Thank you. I guess I'm a bit jittery because I thought I had hit that 'safe' 12 week place, then finding out that actually I haven't has made me a bit on edge.

On a funnier note, if you look at the scan and lean your head to the right, it looks like I'm growing a baby dinosaur

If you're over 9 weeks and saw a heartbeat that's a pretty significant milestone. Try not to worry.