Community post

You can, but it wouldn't be as quick to be positive as a hpt. I had some left after I had gotten pregnant and it wasn't positive until about 20 dpo. It was a digital, too so I know it was positive. The theory behind it is that lh and hcg are a lot alike, therefore the test reads positive.

In addition, the OPK will not for-sure tell you you're pregnant, because other things like ovulation or fertility drugs can cause a positive OPK. If you get a positive OPK after AF is due, it can make you suspicious that you might be pregnant, but it won't tell you for sure, so you might as well take an actual HPT.