OPK Quick Reference Guide

I’m seeing a lot of confusion from ladies at the moment regarding Ovulation predictor kits – or OPKS. As someone who has used them for some time I figured I would share my knowledge on the subject.

What Are OPKs and How Do They Work?

OPKs (Ovulation Predictor Kits) are peesticks! Every TTC’er loves peesticks! They measure the hormone “Leutenising Hormone” (LH). LH is responsible for stimulating ovarian follicles. Before ovulation occurs, there is often a surge or dramatic increase of this hormone, which is what causes the egg to be released from the follicle. The ovulation predictor kits look for that surge by measuring levels of LH in your urine. The surge in LH means ovulation within 12-48 hours.

How Do I Know When an OPK is Positive?

We always have LH in our system, so OPKs don’t work like pregnancy tests. For an OPK to be positive, the “Test line” (The line closest to the part that you pee on) has to be as dark as or darker than the “Control Line” (The line closest to the handle). If it is not as dark or darker, the test is not positive.

Below is an example of OPKs done over a cycle. Everything by the red line is negative. Everything by the green line is positive.

As you can see, there are a few occasions where the line darkens to a point and then lightens back up again. This is because LH fluctuates naturally in our systems.

Some ladies have a “Fade in” pattern, where the OPK gradually goes from negative to positive, but others get absolutely no line and then BAM! Positive! We’re all different, so you have to work out what works for you.

When Should I Use OPKs?

This is different for everyone, and is different depending to the type of OPK that you use. Read the instructions. Most OPKs advise NOT to use first morning urine. The clearblue digital tests (smiley tests) are the only ones I know that advise to use with first morning urine. Everyone’s surge lasts a different amount of time. I know a lady whose surge only lasted four hours or so, but mine lasts closer to twenty four hours.

Consequently, I test twice a day. Once around 10am and once before bed. When the line starts getting close, I will sometimes add in a third test at about 2pm. I’ve never missed my surge, but I’m lucky that mine lasts a fair amount of time.

Do OPKs Work For Everyone?

The short answer here, is no. Some conditions such as PCOS can affect how reliable the results of OPKs are for some ladies. This is because ladies with PCOS tend to have a higher level of LH in their system, meaning some ladies do get constant positives on OPKs, even when they are not close to ovulation. They also can be affected by drugs like clomid, so be sure that if you are using them, you are also tracking via other methods. For what it’s worth, I have PCOS and have used clomid this cycle, but I still only got one set of positive OPKs, which was backed up by fertile mucus and a temp rise over the next few days. Just be aware that no tracking method is 100% accurate. Some ladies find that the line on their OPK never gets as dark as the control but they still ovulate. It’s important to learn your own pattern.

When Should I Inseminate/Have Sex Once I Have a Positive OPK?

Positive OPK means ovulation within 12-48 hours and sperm can live in your system for around five days if you have good fertile mucus. Advice for those who have normal access to sperm is just to have sex every other day. For those of us who use donor sperm, success is slightly higher inseminating on the first positive OPK day. Some ladies inseminate for three days – first positive OPK day, second positive OPK day and the next day too. Basically, if you have a positive OPK be sure to get some sperm in there waiting for the egg.

If I Get A Positive OPK, Did I Definitely Ovulate?

In most cases, an LH surge precedes ovulation by about 12-48 hours. Inm some cases, however, your body will start trying to ovulate and fail. It is possible to have several attempts to ovulate in your cycle and several LH surges. This is why it is important to track by something other than OPKs as well. Taking basal body temperature is a helpful way to confirm for sure when you have ovulated. Fertility Friend is a great resource for learning about BBT charting.

I Heard That OPKs Can Be Used as Pregnancy Tests?

They can! LH and HCG (the pregnancy hormone) are from the same family of hormones. Imagine that LH and HCG are both clowns, but LH is wearing a hat and HCG isn’t. Consequently, OPKs can pick up HCG and will show positive if you are pregnant. However you should not attempt to use OPKs to predict pregnancy. There are several reasons for this – the first one being that some women get a surge in LH just before their period starts. The other reason is that if there is enough HCG to turn an OPK positive, it will also turn a pregnancy test positive. So, don’t waste time using OPKs as pregnancy tests – although it is fun to do once you know you’re pregnant! Here’s a couple of tests that I did when I was pregnant with Squishy – The green is an OPK and the  blue test is a pregnancy test.

I Use an App to Track My Cycles. Should I Still Use OPKs?

You don’t have to. As I said, no one way of tracking is 100% accurate. However, apps are the most inaccurate. Especially if you’re a couple with limited access to sperm. Apps go by averages, so they might be working things out wrong every single month for you. I have been tracking my cycles with Fertility Friend for the last three years, and even now it still sometimes doesn’t make a correct prediction. Use as many methods as you can to track your fertile period. No way is 100% accurate.

Aren’t OPKs Expensive?

Yes and no. Some brands are. Clearblue Digitals will set you back around £30 for a box of twenty. First Response OPKs cost about the same. However, have a look on ebay and Amazon. I pick up 100 OPKs for about £15. No, they don’t make a happy face when you’re close to ovulation, but they do work and they do cost a lot less. It’s all about what you want to spend – there are options for everyone.

So, To Round Up!

– An OPK is ONLY positive when the test line is as dark as or darker than the control line

– A positive OPK means ovulation in 12 to 24 hours, not that you are ovulating right now.

– Always use more than one method to track your fertile period as no method is 100% effective