How do HPTs work?
Home pregnancy tests look for hcG in your urine. This is one of the first
hormones produced when you are pregnant. The amount of hcG in your
system in the week before your period is due can vary from pregnancy to
pregnancy. It isn't necessarily a sign of the pregnancy's viability or a multiple
vs. singleton pregnancy. In the week before AF arrives, most pregnant
women have 5 - 50 mIU of hcG in their system. That number should double
every 2-3 days. The most sensitive HPTs typically test for 25 miU. See HPT
When will I have hcG in my system?
The pregnancy hormone hcG will start to be produced after implantation, not
at the point of conception. So if you ovulate on CD 15, you may have
conception occur on CD 16, then implantation occur six days later at CD 21
(or 8 DPO). Most pregnancies implant at approximately 9 DPO (give or take
a day). After implantation it can take several days for the hcG to build up in
your system enough to trigger a BFP. With an early test, the earliest it is
"reasonable" to start testing is at around 10 DPO.
When Can I Test?
The two week wait can seem like an eternity. How early you can test
depends upon the sensitivity of the test and the number of tests you are
willing to 'waste'. Generally, the most sensitive tests (such as First
Response Early Response or EPT, for example) suggest you can test "Five
Days Before your Missed Period". What this really means is five days before
CD28, assuming ovulation on day 14. (This type of cycle is considered the
standard even though few women have such a cycle.) This translates to 10
DPO being the first day you could possibly see a BFP if you are pregnant.
Many women, though, won't see a BFP until 12 DPO - or even later. See HPT
How Early Can I Expect to See a BFP?
HPT accuracy by DPO:
10 dpo : 35%
11 dpo : 51%
12 dpo : 62%
13 dpo : 68%
14 dpo : 74%
15 dpo : 80%
16 dpo : 88%
17 dpo : 92%
18 dpo : 99%
So if you are pregnant, there is still a 65% chance that you'll get a BFN at 10
DPO. About 25% of pregnant women still get BFNs at 14 DPO. The queen
cannot vouch for the accuracy of these stats given todays' more sensitive
tests... but the point is that just because you get a BFN at 10 DPO, and your
test claims you can test as early as 10 DPO, it doesn't mean you aren't
pregnant. You might find this FAQ helpful.
Do faint lines count?
Yes. Generally speaking, any test line indicates pregnancy assuming you
have followed the instructions of the test. A faint line could indicate a low
level of hcG, which is to be expected if you are testing early. It could also
simply mean that particular test didn't have much dye. If the line is gray or
colorless, you may be looking at an evaporation line. Now, if you see your
"faint line" only after breaking the test apart, holding it up to 5 different types
of light, scanning it and adjusting the color contrast... that is a different story.
Do I have to use FMU?
Instructions for just about every home pregnancy test make it sound as if first
morning urine is the ONLY urine that can be used for testing. This isn't true.
The idea is that FMU is the most concentrated, and therefore would have the
most concentrated amount of hcG. But depending on numerous variables,
you may find that second morning urine works better... or even late evening
Here is an example from her royal highness's personal collection. As you
can see, second morning urine (SMU) provided a darker line than first
morning urine (FMU).
What does 99% accurate mean?
It's important to understand what this does not mean: 99% accurate does
NOT mean that if you are pregnant, the peestick will give you a BFP 99% of
the time. Far from it. Accuracy ratings on peesticks refer to how often their
peestick compares to clinical peesticks. So if a peestick used in a doctor's
office picks up a pregnancy, a peestick that claims 99% accuracy will pick up
that same pregnancy with the same pee 99% of the time.
Do the lines on digital tests mean anything?
Like any sane and rational ttc'er, you may have torn open your digital HPT as
if to say "are you SURE you meant to say I am not pregnant?" In doing so,
you likely discovered a test strip that looks just like an analog peestick. You
may have also discovered that test has two lines and thought "ah-HA! See? I
am not crazy, I am pregnant!"
Unfortunately, you may be both insane and not pregnant. Digital tests are
different from regular peesticks. The test looks not just for the presence of a
second line, but it also reads the intensity and color of that line. It looks for
variances that the human eye cannot detect. These tests are not meant to
be torn apart. If your digital test says "not pregnant", do yourself a favor and
resist the urge to pop open the casing.
Here is a dissection of a digital test (in this case an FRED). The top test is
positive, the bottom test is negative.
How do OPKs work?
Ovulation tests detect lutenizing hormone (LH). This hormone surges 12-48
hours before you ba-GAWK (or release an egg to those of you that don't
speak chicken). On a positive OPK, the test line must be as dark as (or
darker than) the reference line. Be sure to read the results within the time
limits specified in the instructions. Tests often darken after the time limit
which can results in false positives.
How soon after an positive OPK should we DTD?
Her majesty prefers to not tell her subjects how to conduct their bedroom
affairs... but since you asked... It is generally recommended to DTD the
same day as the positive OPK and the next two days as well. If your partner
has low sperm count, you may want to try DTD every other day instead.
Charting can be a useful way to see how soon after a positive OPK you
typically ovulate. The best days to DTD is the day before and the day of
What if I never get a positive?
Try testing twice a day - perhaps once with SMU and once in the late
afternoon. Some women have very short LH surges, and unless they test
twice a day they can miss the positive.
Can I use an OPK as an HPT?
Many ttc'ers like to use OPKs as HPTs for fun and sport. How effective is it?
Check out OPK as HPT and decide for yourself.
Disclaimer: Always consult
your doctor for medical
advice, not a
website...especially not a
website called Peestick
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