Help calculating due date - no period between pill and pregnancy

[woollymammal99]

I last took the pill on Saturday 20th April. I had what I think was a withdrawal bleed from about Monday 22nd to Friday 27th. I'm not sure if this could've been a period? I was taking ovulation tests... On Saturday May 4th it said no fertility, and on Sunday May 5th it said peak fertility. So I never had a high fertility result, only peak. I didn't take any ovulation tests after this. I took pregnancy tests after this, and stopped once it was still showing negative on Wednesday May 22nd. But then my period didn't come, so I tested again Wednesday May 29th. This test was positive. A second test on Friday 31st was also positive.

My main question is, how can I calculate my conception or due date? I'm confused by what I've read online, could my withdrawal bleed have been a period? I'm also confused by all the negative test results considering when I was in peak fertility...I have read you don't conceive bang on your first peak fertility day, and it takes a few days for you to ovulate and for the sperm to fertilise during this time, implant and so on. I don't understand how long these first processes take. So could this explain, or could I perhaps have ovulated again later in the month and conceived then instead?

I'd really appreciate anyone's insight or guidance on anything mentioned here. Thank you so much!

Hi @woollymammal99

I'll try to answer a couple of your questions (I am a healthcare professional working in this field):

1. If you were on either the combined pill, or the desogestrel progestogen-only pill, and were taking the pill correctly, the bleed you had would have been a withdrawal bleed rather than a period. This is because both of those methods are very effective at suppressing ovulation, and strictly speaking a period refers to a bleed which follows ovulation (generally about 14 days after ovulation). Old style POPs such as Noriday or Micronor are less effective at suppressing ovulation though. Can you remember the name or brand of pill?

2. It takes between 6 and 18 days for a fertilised egg to implant into the endometrium, with a mean of 9 days. So if you're on the slower end of that spectrum, it could explain why your initial pregnancy tests were negative (the pregnancy hormone,beta hCG, will only be detectable in your urine following implantation). This is why health care professionals wait 3 weeks after an episode of unprotected sex before relying on the result of a pregnancy test.

I hope your positive pregnancy test was good news for you and I wish you all the best

@MiniJellyBeans thank you for your time and help! I only ever took one pill, the Cerelle mini pill, and I was good at consistently taking it within the same hour every day. I took it for one year, but in the last few months of taking it I took breaks as I was having such a bad experience with side effects. Yes, our positive result is extremely positive for my partner and I, thank you so much! 🥰 I suppose the first scan will clear up any questions about my conception/due date, if I understand that right? Thanks again!

Yes the dating scan will give you a pretty accurate expected date of delivery. EDD tends to be based on scan measurements rather than periods anyway.
Congratulations and all the best.

This exact thing happened to me. They initially assumed my withdrawal bleed was a period, booked me in as normal, but at my scan I was only 9 weeks so had to come back in 3 weeks time
Congrats

same as above, I had been on the pill and didn't have a period in between stopping the pill and getting pregnant, so instead the midwife worked out my dates roughly from the withdrawal bleed, its not accurate by any means but its a start :) good luck and congratulations on your pregnancy.

I had this; I used one of the pregnancy tests that can tell you vaguely and then had a dating scan that I paid for as I was concerned that that midwife was counting what was a implantation bleed as a period; based on my actual dates the midwife would have been booking me in for 14 week scan so I’m glad I paid for one that demonstrated my actual dates

I stopped taking my pill in August i was on the pill where you don’t have a break I took everyday, I had sexual intercourse from the 24-30 August and then I had a light bleed 2/3 September I am currently 18 weeks pregnant when did I conceive would it of been from sexual intercourse in August? I’m confused because of the light bleed I had.. when I read online it gets confusing

If you’re currently 18 weeks then conception would have been 16 weeks ago, around September 15th. Sperm can survive for some time after intercourse, but unusual to be more than 5 days. So your pregnancy most likely resulted from intercourse around 10th-15th September - this is a bit outside your earlier dates, it’s unlikely that you conceived in August. Your bleed in early September sounds like a lighter than usual period and would tie in with ovulation/conception a couple of weeks later, matching your gestation/due date.

I hope this isn’t a worry for you and that all is ok with you and baby x

@Emmzo Thankyou for your reply, the bleed on the 2nd wasn’t a period as I bleed normally for 4-5 days. My pregnancy has been measured from the 2nd September o thought that was from implantation but when I read online I see something about two weeks added on that you’re not pregnant that’s what confused me so I’m only technically 16 weeks pregnant? X

They still add on 2 weeks even though the first 2 weeks baby isnt there, so you will still be dated 18 weeks pregnant x

@BusyCaz oh okay that was never mentioned during ultrasound I was told they date from day baby implanted as there was no LMP to go from, I have a friend who is due 2 days before me and she conceived in August. Very confusing when they add weeks on 🤦‍♀️ thanks for replying

It is confusing. They calculate baby and pregnancy from 2 weeks before implantation. Google may explain it better than me, but that is how they work out a due date x

@BusyCaz yes I have read on Google even that I don’t find very clear sometimes it has mixed things written on there so many peoples date are different from when they last had LMP. When I had an ultrasound she told me this measures from baby implanted but then I was having a read online and thought this don’t make sense lol, I only had intercourse in August so my due date baffled me for a September conception x

@BusyCaz sorry was meant to write my friend only had intercourse august not me, and we are due 2 days apart so I have no clue how that works out x

Hi, so I started taking the progesterone only pill on the 29th of January and with this pill you take it continuously, I took it the same time every single day. On the 27th of February I missed a pill but took two the following day. I then missed my pill on the 1st and 2nd of march then received 2 positive pregnancy test results on the 3rd. I’ve had a lot of unprotected sex and protected sex. I’ve have two potential fathers but am unsure who the father is. I’m also unsure of how far along I am as I took a pregnancy test on the 18th of February and the results were negative. I’m unsure of when I actually got pregnant. I also had no bleeding at all. My last period ended on the 6th of January. Any help would be greatly appreciated!!