How to calculate due date for irregular period

lhotkami

So, I just found out on my 30th Bday that I am pregnant!  But I am wondering how to calculate a due date when you have irregular periods.  My last period was July 1, but they average 39 days.  In addition I took a test 7 weeks after my last period and it was negative (even with First Reponse early result).  Then I took one this week (8 weeks 3 days from last period).  Due to my longer periods and negative result last week I am not thinking I am really 8 weeks and 5 days).  Anyone have a guess as to how far along I really am?  I am guessing maybe 5 or 6 weeks, the thing is that I have 3 weeks yet to wait for my appt.  Any help or opinions is appreciated!!

monica93555

It's hard to know without a ovulation date or an u/s. I would personally just go with the first day of your last period (assuming you don't know when you ovulated) until you get that u/s!  I know it's hard to wait for it though!

skidderdo

You're right, 6-ish weeks is probably a more accurate estimate. It usually takes a LEAST 10-12 days for the urine pregnancy tests to pick up a (+) after ovulation. That being said, you should definitely have a dating ultrasound to confirm your dates. Congratulations, by the way, what a wonderful birthday surprise!

Fremdschamen

I'm no expert, but I don't really think there is a way to tell if you don't know when you ovulated.  You might just have to wait till your appointment, and then hopefully they will give you a dating ultrasound.

aislinnanne

This site will let you put in the length of your period. I don't know how accurate it is but it's somewhere to start. 

https://www.justmommies.com/duedate.shtml

Ooglybear

I'm in the same boat as you, waiting for a dating u/s in 1.5 weeks. Good luck!

lhotkami

Thanks aislinnane, the justmommies site worked very well, it also lines up exactly with a date we did the baby dance!  And also I forgot to mention I spotted on Aug 4, so this lines up with that as well, just seems so weird it was negative last week, I guess maybe that was just a fluke!  Thanks everyone!!

danuli8

It can take a while even after spotting to get a + result. I had implantation spotting July 29 but an ept test on Aug 6 was still negative. I didn't test again until my husband noted that I had been PMSing for 3 weeks straight and finally got a + test on Aug 20. I counted back 7-10 days from my spotting, which gave me April 9-April 14 as the EDD range, and today's u/s gave me April 7, so the spotting is actually a pretty good way to guess when you conceived.

dklb08

I am in the same boat. My LMP started on 7/15. But, my cycles have been WAY off since ds. Some as short as 3 weeks others as long a 8 weeks. My ticker is based on LMP. I did get a BFP on the early side. But, it was SUPER faint. I ended up buying a digital to be sure. then took the same +/- test a week later and the + was very clear. Since i have no idea when i O'd, I made my appointment late to make sure there was a HB. My 1st appointment in 9/21. I will either be almost 10 weeks or get a new EDD

aislinnanne

lhotkami:

Thanks aislinnane, the justmommies site worked very well, it also lines up exactly with a date we did the baby dance!  And also I forgot to mention I spotted on Aug 4, so this lines up with that as well, just seems so weird it was negative last week, I guess maybe that was just a fluke!  Thanks everyone!!

You are very welcome! Good luck with everything!