Could an OPK give me a False Positive?

Hey Kindara!

I’m still fairly new to charting, and I’m a little confused about how to read something. My 1st month the charts were easy to follow, but this month they’ve been harder, so I’ve been doing an OPK test every day to be safe. On Saturday I tested negative at 11am, on Sunday I tested positive at 11am, I wanted to double check so I tested again around 5pm and it was negative. Was the positive a false positive or does it normally have that small of a window? Very confused, any guidance welcome, thank you!!-Kiki30Confused Central

Hey Kiki,

OPKs are sensitive to luteinizing hormone surges. These surges are caused by an increase in estrogen and are often quick. Therefore, getting a positive at 11 am and a negative six hours later is not only possible, but likely, as your LH surge may have started as early as noon on saturday and “finished” before 5 pm.

To help confirm that ovulation actually happened, we’d have to see your cervical fluid and basal body temperature(BBT) information for this cycle. In general, your cervical fluid will become more fertile leading up to ovulation and your BBT will rise and stay high following ovulation. These are great ways to understand if an OPK is giving you a false positive or not. If you like using OPKS we recommend using them in addition to charting your BBT, as BBT is the only way to be sure you ovulated without getting tests done with your healthcare provider.

Stay in the know

We believe in TMI (too much information) in a good way. Enter your email below for blogs and occasional emails from Kindara with charting tips, updates, and offers.
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form
Meet your fertility goals and better understand your body with the world's most powerful and useful fertility charting system.