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There are several different ways to determine when you ovulate (including observing your cervical fluid, charting your temperature, and using an ovulation predictor kit). If you’re new to all of this, I suggest you check out my post first on 5 Things to do When You’re Not Getting Pregnant Right Away. And if you’re not new to this and want to find out the answer to the question I always had — how long after the LH surge do you ovulate (because it can be confusing even when using an OPK) — then keep scrolling past “the basics.”
Although observing your cervical fluid and charting your temperature are arguably the MOST reliable methods of tracking ovulation (according to my go-to book for all things fertility, Taking Charge of Your Fertility), I’m personally a fan of OPKs (even though I was very hesitant to try them at first!). Using an ovulation predictor kit is easy, fairly unambiguous, cheap, and reliable (unless you have an LH surge but don’t actually ovulate…which is possible, as you’ll see below, but still not super likely).
The basics: How do OPKs work?
Ovulation predictor strips test the level of LH (luteinizing hormone) in your urine. The LH surge (rise) occurs right before you ovulate, so using these strips will tell you when the best time is to have sex in order to maximize your chances of getting pregnant.
The basics: How do I do it?
First, buy an OPK (I recommend this one–Easy@Home–from Amazon, as it’s cheap and pairs with the free PreMom app).
Download the PreMom app. The app will let you take a picture of your test strip and analyze it for you! So you don’t ever have to wonder…is the test line actually getting darker? (When the test line is as dark or darker than the control line, it means you have your LH surge.)
Then, start testing! It’s typically recommended that you test every day around the same time, beginning on day 10 of your cycle until you get a positive result. A positive result means you’re about to ovulate, which is when your most fertile time is.
Sounds easy, right? Okay, not so fast. Here are some issues, possible complications + FAQs that I had to do a little research to figure out:
What if I never get a positive?
I’ve never had a problem with this, but I know it’s possible. For some people, the LH surge lasts less than 10 hours…so let’s say you test at 10am one day and 10am the next day…you may have missed it. If you never get a positive, you may have to check more than once a day. (Or use one of the other methods of tracking ovulation!) It could be that you didn’t test early enough, too–
What if my cycles are super irregular?
You might have to test earlier than day 10…and keep testing for a long time. Yes, that’s annoying, but I still think it’s worth trying. The Easy@Home tests include FIFTY test strips.
What if I have multiple days of positive?
This is me, and it’s totally normal, but again this is why I could never figure out when exactly I ovulated. First, though, the research says: Some women have “rapid‐onset type” LH surge (within one day, 42.9%) and “gradual‐onset type” LH surge (over 2–6 days, 57.1%). So multiple days of a positive result are not a bad thing. Actually, that can be more helpful, except the question remains–
When EXACTLY do I ovulate?
This was always my question that I could never find the answer to. (When I have multiple positive days…am I ovulating the first day or the last?!) I finally pinned down the answer after I studied some of the clinical research:
The onset of LH surge typically comes 35-44 hours before ovulation. The PEAK level of LH comes 10-12 hours before ovulation.
BUT keep in mind WHEN you test. Let’s say you test every day at 6pm. If you see that the test line is beginning to get a little darker (onset of the surge), that doesn’t necessarily mean you will ovulate 35-44 hours later. Maybe your LH surge actually began the previous night, after you had already tested. Or in the middle of the night…
Just in case you’re wondering: In that same study, the onset of the LH surge usually happened between midnight and 4am (37%) or 4am and 8am (48%). Soooo….the first time you see the line begin to get darker, that’s the onset of the LH surge, but it likely actually happened between midnight and 8am of that day.
As you use these things, you’ll figure out your LH surge and how long it typically lasts for you. The important thing is that you ovulate 10-12 hours after the PEAK LH surge (the last positive result — but again, depending on when you’re testing.)
So when’s the best time to have sex to maximize my chances of getting pregnant?
Again, this is tricky, because people have different types of LH surges. Since sperm can live in your body up to 5 days, and your egg is viable for 12-24 hours after ovulation, you could get pregnant anywhere from 5 days up to and 1 day after ovulation. So, if you have a gradual-onset LH surge, that actually helps you time it a little bit better. Actually, studies have shown that your best chance of getting pregnant are the 2 days before and up to the day of ovulation.
Some other notes on what could go wrong…(aka why my go-to book doesn’t like OPKs)
1. In the study I keep referencing, 10% of women had an LH surge but never actually ovulated. So, it’s possible.
2. If you have PCOS, your body might keep producing LH surges…which may be a sign to you that you have PCOS…but won’t help you when figuring out when you ovulate.
3. Some fertility drugs may invalidate the test.
All that aside, however, the VAST majority of women DO benefit from using these. Several of my friends believe they got pregnant because they used an OPK. My doctor even told me he wouldn’t do any testing until I had used an OPK to try to time intercourse first!
Thank you that was helpful. I’ve found forum topics of women in Germans who thought they’d have 24 hours up to 30 hours after the LH strip shows positive. Next morning they had an ultrasound and:…. the follicle ruptured and the Egg was already on its way. Without them having had Sex and their husband off to work… So when husband would come home to have Sex the egg will already at least be 12-16 hours old!!!
My advice: have Sex the moment the strip shows LH… then again 2 days later😜