Home pregnancy tests are testing for hcG.  Ovulation tests are testing for
LH.  Chemically, these two hormones are extremely similar.  So similar, in
fact, that hcG is mistaken as LH by ovulation tests.   (A home pregnancy test,
however, does not mistake LH for hcG.)

Given that ovulation tests are cheaper than home pregnancy tests, frugal
peestick enthusiasts often want to know if they can simply use OPKs to test
for pregnancy.  The answer?  Yes... BUT

  • a HPT will almost always pick up on a pregnancy before an OPK

  • only a HPT will confirm you are pregnant. A positive OPK could mean
    you are ovulating.    

  • this isn't what OPKs were intended to do, so don't blame the
    peesticks when they don't bow down to your madness


(More acronyms, please!)

"I'm 10 DPO and have a second line on an OPK, but it isn't positive.  Could
I be pregnant even though the OPK was negative?"

You could be pregnant, but that OPK isn't telling us much.  Many ttc'ers who
use OPKs as HPTs find that they get a positive on a HPT before the OPK.
Here is an example from the queen's personal collection.   As you can see,
the HPT is faintly positive at 9 DPO.  The OPK (on the bottom) isn't quite
positive yet, even at 10 DPO

The OPK did indeed turn positive, but it was days after HPTs had already
given a BFP:

"I'm 13 DPO and have a second line on an OPK. Could I be pregnant?"

The OPK must be positive (meaning the test line is as dark or darker than
the reference line) to even be given consideration.  Many women always
have at least some test line on an OPK.

Here are OPKs taken daily from the point of ovulation until the arrival of AF:

"My OPKs have been getting darker since 6 DPO. Could I be pregnant?"

The darkness of OPKs can vary for a variety of reasons, most not pregnancy-
related. The amount of dye can vary from test to test.  More concentrated
urine can cause a darker line to appear.  Daily variations in the amount of
post-ovulation LH can also cause the OPKs to appear as if they are getting
darker.  Of course, yes, you could also be pregnant - but the odds of the
OPKs telling you this before 12 DPO are just about nil.  (Unless you aren't
sure about your date of ovulation.) You are probably making your eyes cross
and driving yourself into ttc-psychosis if you are comparing the darkness of
one test to another.  Just step away from the peesticks for a few days, test
again, and then compare. If they really are getting darker, your test at 10 DPO
should be noticeably darker.   In fact, a HPT will give you a straight answer.
TTC Store
Disclaimer: Always consult
your doctor for medical
advice, not a
website...especially not a
website called Peestick
Paradise.  Copyright 2009
2014. All rights reserved.
Click here for the