Just info for ladies waiting to get their BFP.

[beth30]

A pregnancy test becomes positive only after the fertilized egg has first implanted into the uterus and then send enough amounts of hCG the pregnancy hormone into your blood stream.

Implantation, when the fertilized egg implants into the endometrium, happens about a week after ovulation (range: 6-12 days), and it takes another 3-4 days after implantation (9-10 dpo: days after ovulation) for the blood pregnancy test to first become positive.

Blood Pregnancy test: If you are pregnant then the blood pregnancy test is usually positive within 3-4 days after implantation or about 9-10 days after fertilization and ovulation.
Urine (Home HPT) Pregnancy Test: The urine pregnancy test will usually not become positive in most women until a missed period or about a week after implantation. Many manufacturers of urine pregnancy tests want you to believe that the urine test is usually positive before a missed period, but only about 25% of pregnant women will test positive with the HPT 2 days before a missed period, and about 40% the day before the missed period. On average, a pregnancy will be positive 13.5 days after ovulation, or about the time you expect your menstrual period.
The wide variation of when the urine pregnancy test becomes positive and how early can pregnancy be detected are due to four variables which determine when the home urine pregnancy test becomes positive:

1.Timing of Implantation
2.Blood hCG levels
3.Urine hCG level (eg.how concentrated or diluted the urine is)
4.Sensitivity of the pregnancy test


1. Timing of Implantation
A pregnancy test detects the presence of the pregnancy hormone hCG (human chorionic gonadotropin) either in the blood or in the urine. The hCG in the urine comes from the hCG in the blood after it was filtered through the kidney. After ovulation, the egg gets fertilized and travels through the fallopian tube toward the uterus. This travel takes on average about a week. Implantation, the attachment of the fertilized egg in the lining of the uterus, occurs on average about a week or later after ovulation/fertilization, but it can happen as early as six days and as late as 12 days after fertilization/ovulation. At the time of implantation, the placenta starts making the pregnancy hormone hCG, which then enters the blood stream. How early can pregnancy be detected depends onthe pregnancy hormone hcG which can be detected in the blood about three to four days after implantation. Urine hCG can be detected about two to three days after blood hCG can first be seen. Detection of hCG depends on timing of implantation, so hCG can normally be detected in the blood between nine and 16 days after ovulation (HPT: 12-19 days after ovulation).

2. Blood hCG Level
There is a wide normal variation of hCG levels, both in the blood and the urine and this wide range changes the diagnosis of how early can pregnancy be detected. If a woman has low blood hCG levels, for example, then it can take several more days for it to show up on a pregnancy test.

3. Urine hCG Level
Urine hCG levels change over the course of the day depending on how much you drink and how diluted or concentrated the urine is. Urine pregnancy testing is best done with more concentrated urine. So how early can pregnancy be detected depends on the urine concentration. If you drink a lot of fluid, the urine may be too diluted early on in pregnancy to achieve an hCG concentration adequate enough for a positive test.

4. Sensitivity of Urine Home Pregnancy Test
Different pregnancy tests have different sensitivities and that has an impact on how early can pregnancy be detected. The lower the sensitivity, the earlier a pregnancy test becomes positive. Sensitivities are indicated in mIU/mL, the lowest amount of hCG in the urine that tests positive. A sensitivity of 20 mIU/mL requires one-half the hCG level to be positive when compared with a 40 mIU/mL sensitivity level, and it may become positive several days earlier than the pregnancy test with a higher sensitivity. Make sure you read the package of the pregnancy test to determine your pregnancy test's sensitivity.

This information is from the following website: https://www.babymed.com/pregnancy-tests/pregnancy-test-when-does-it-get-positive

 

[beth30]

Last time I was about 10dpo when I got a positive test. But that isn't always the case. So I thought this would give some hope. My positive with my son wasn't until after my missed period.

 

[MrsPsandQs]

Some interesting info, thx!

 

[waiting2012]

I guess I am one of the few women who doesn't follow the textbook...

My bfp with my now 11 year old dd was very early--6 or 7 dpo--confirmed by u/s and labs that I was ONLY 4 weeks a week AFTER taking the hpt.

I have found out just last night--pg again-- (+) hpt last night and this am. They are faint, they are pink and they are seen within the time limit.

Ovulation occurred last weekend--cramps like AF was about to let loose on wednesday for 2 hours only....

We bd'ed thurs, friday, saturday, sunday and monday (skipped tuesday and wednesday). Sure of O' happening sunday as I had left sided pain in ovary area and was very "wet/ewcm"y...at around 5pm on that day. That makes Wednesday 3 dpo. It can happen--just doesn't happen that fast for everyone...I would love to see a study on how a woman's body make up helps or hinders implantation, ie... the length of the woman's fallopian tube etc...Men are different length--why wouldn't we be...

Either way--I do know that--the pg that I did implant late with--I m/c'ed...as I wasn't get BFP's till 11/12/13/14 dpo or later...and my sx weren't near as strong as they have been since wednesday...It's like being pg with my 11 year old all over again this time...!

Good Luck Ladies....Everyone is different...

Luv,Stephanie

 

[PandaLuv31]

Thank you so much! This info is very helpful.

 

[jbell157]

So since I drink a ton of water, because I'm thirsty all the time, I could still be pg even though I'm 8 days late and have had 3 bfn? Hmm. I've pretty much decided I'm not pg because of the last bfn I got yesterday. Im not sure now

 

[Mrskg]

Thanks Beth x so going by this from implantation to urine bfp it could take between 5an7 days, this so gives me hope if I ov'd a wee bit later than I though an I implanted on wed it could take till mon or even we'd before bfp an would explain my bfn or I could come back down from my bubble an admit it could also be the witch playing games with me!

Congrats waiting2012xxx

 

[Mrskg]

I found this article about hcg helpful too

https://www.baby2see.com/preconception/hcg.html

 

[sarahwantland]

I want my BFP so bad right now. I know that I am preggers. I guess I am waiting for implantation right now. Or, may be for the hormones to go up enough. Anyway, thank you for the information. I am getting so irritated with waiting. I mean, my bbs hurt, I am dizzy, and I can smell someone's lotion standing ten feet away from me. I just want the confirmation because I am afraid that this is all a sweet dream.

 

[beth30]

Thanks Mrskg! I also read something on bnb a few weeks ago about the different horomone that goes with a beta, there is also and alpha, and sometimes the hpts pick the alpha up and not the beta, and then if the pregnancy doesn't succeed the beta remains low.... or something like that... probably got it all wrong, so don't take my word for it. (my new doctor mentioned something like that as well)

 

[cochy115]

Excellent, Beth! Thank you!

 

[beth30]

OMG! I FINALLY FOUND IT!!

False Negative Pregnancy Tests
A false negative pregnancy test means that the test tells the patient they are not pregnant when they really are. Why does this occur? There are four well known reasons pregnancy tests can give false negative results.


1) The most common reason is testing too early after fertilization occurs. The pregnancy hormone, hCG, is not produced until implantation occurs and it takes several days for the hCG concentrations to get high enough in blood and then urine to give a positive signal. Most devices give positive results around the day of a woman's expected period, but this can vary widely.

2) Another reason for false negative results is dilute urine. If a woman drinks a lot of fluids, the concentration of hCG in the urine will be more dilute. For this reason many doctors recommend that testing be performed on the first urine of the morning because this tends to be the most concentrated (because you probably have not drank anything all night long).

3) A very rare cause of false negative results occurs when very, very, high concentrations of hCG are present. This is called the high-dose hook effect. The hCG assays works by forming a so-called "sandwich" with two different antibodies as the "bread" and the hCG molecule as the "meat." The hook effect occurs when the hCG concentration is so high that it saturates both antibodies and there are so many molecules that the antibodies don't actually form a sandwich. This is rare because women don't normally produce enough hCG to saturate both antibodies. The hook effect should be of concern in a hospital setting, but most women should not be concerned about a hook effect with their urine. A hook effect can be confirmed if testing shows a positive result after sample dilution.

4) Finally, the other reason for false negatives was only recently described and is referred to as the "variant hook effect." This is much more common than the hook effect. As pregnancy progresses, there are actually different variant forms of hCG that begin to appear in the urine. After about 5 weeks of pregnancy (i.e. 3 weeks after the expected period) concentrations of hCG beta core fragment are higher than all other forms of hCG. This is perfectly normal. Unfortunately, the concentration of hCG beta core fragment can saturate one of the antibodies used in the assay in certain pregnancy kits, and the other antibody doesn't recognize the beta core fragment. As a result, no sandwich forms and the test is read as a negative. The farther in pregnancy a woman is, the more likely that this false negative will occur. Similar to the hook effect, the variant hook effect can be confirmed if testing shows a positive result after diluting the sample.
Posted by Ann M. Gronowski, PhD 5/8/11



Here is the site I got the info from:
https://www.pregnancylab.net/hcg-variants/

 

[beth30]

Just bumping this because I feel like the info needs to be shared.