Due date - Short cycles?

[BrightLilacCat]

I’m trying to figure out my dates and hoping someone can advise as I’m wanting to get an early scan at 8 weeks. I’ve read that if all is well at 8 weeks the likelihood of a successful pregnancy increases.

• LMP 02/01/2025
• Ovulated 13/01/2025 (CD 12, LH peak CD11)
• BFP 22/01/2025 (CD 21, 9 DPO)
• I’ve been having variable cycles since coming off the pill but my luteal phase is fairly fixed so I’d have expected my period on 25/01/2025 so a 23 day cycle based on the timing of ovulation.

On the NHS due date calculator when adjusted to a 23 day cycle it makes me currently 5 weeks + 1, yet on a 28 day cycle it makes me 4 week + 3.

The scan company’s website is only bringing up the option to book based on my LMP date. Would you book the timing of the 8 week scan based on a standard 28 day cycle or my shorter 23 (ish) day cycle? I know it’s only 5 days difference, but I’m feeling quite anxious about the pregnancy and would like the reassurance at as close to my actual 8 weeks as possible.

If you ovulated on day 12 you should only be 2 days earlier than a typical cycle, it could have been day 11 you ovulated? I usually ovulate the day after my lh peak but it can vary for everyone. The way they do the initial lmp is they assume people ovulated on day 14 of a 28 day cycle.

I ovulated on day 24 once, so I just did ovulation - 14 days for my estimated lmp.

I would say you are ~4+6 now.

The cycle calendars are likely assuming your luteal phase is 14 days.

Thank you @Blue2020 for your insight. I could well have ovulated on CD11 because I wasn’t measuring BBT, just LH strips. My luteal phase was always 11-12 days so that makes sense with it being a bit before the assumed date. I think I’m going to book the early scan as close to possible to 8 weeks based on my LMP - if I’m over 8 weeks, great, but I think if I was under 8 weeks I’d just want to go back again! It’ll be interesting to see what my actual due date is when it’s calculated at the 12 week scan.

@BrightLilacCat It might be a good idea to book it for 8.5-9 weeks instead? Early scans can be out by a few days due to how small it is and the machines accuracy.

An example- I knew my ovulation annd used that -14 days for my lmp and with my son they put him behind by 3 days at a 9 week private scan. However by the 12 week dating scan he was two days ahead. Im pregnant again this time and luckily only got put one day behind at a 8 week scan at epu but that was transvaginal, by the 12 week scan the baby was ahead by two days again.

For both of mine the due date has been set two days ahead, which is pretty close really.

Thank you @Blue2020. I hadn’t considered that with it being so small at an early stage that there is likely to be some variation in dates. I’m going to hold off on booking the scan for as long as possible. I’m travelling overseas for work alone when I’ll be somewhere between 8 and 9 weeks and hoping to get some reassurance before I leave. The idea of finding out something is wrong when overseas and alone terrifies me!

I have very short cycles and ovulate on CD10-12.

Just use your LMP for the scan at 8 weeks

I don’t know how but I’ve been measuring 6 days ahead on all of my scans. Should only be 2 days ahead based off ovulation dates but here we are!