So you want to get meaning. Like, now. You've heard a lot of women accept had success with Ovulation Predictor Kits (OPKs), which test for a surge in Luteinizing Hormone (LH), and so you're interested in stocking upwards on those. The only problem is, y'all're not quite sure what LH is, how OPKs work, or whether your surge is dissimilar from another woman'south. And of form, you demand to know everything. Like, now. We've got answers. Let's begin!

What is LH?

Your brain is pretty smart, right? I'd say genius – did you know your anterior pituitary gland, which produces your reproductive hormones, the masterminds of your fertility, is located in your brain? That's right, hormones produced in your brain play a leading part in releasing a unmarried egg from an ovary in your uterus and helping yous achieve pregnancy.

The hormone responsible for triggering your ovary to release an egg, and ovulate, is Luteinizing Hormone, or LH. After a dominant egg has grown large enough for ovulation and your body has produced a big amount of estrogen, LH product, which is low throughout your cycle, ramps up and upwards over a menses of days until it 'peaks' or 'spikes,' signaling for your body to release the ascendant egg in hopes of achieving pregnancy.

How do I know when LH peaks?

LH is a very popular hormone amid women – just not but because it signals the beginning of ovulation. It'southward as well a superstar because it tin be detected and measured through urine, giving women the power to know when they volition ovulate – at home and at a reasonable price. How? With Ovulation Predictor Kits (OPKs).

What are OPKs?

OPKs are strips (very similar in appearance to pregnancy tests) that comprise a substance that turns red if an LH threshold, or high enough LH concentration, is met. Like pregnancy tests, either 1 or two lines will turn red – the 'control,' to know the test is working, will always plow scarlet (wait closely on the exam to see the control line indicated) and the LH test line volition but turn ruby if your LH is 'peaking.'

LH Surge: When to Detect Peak Fertility with an OPK

How soon after an LH 'peak' will I ovulate?

Ah, the million-dollar question! The elementary answer is – it depends. On you. Every woman and her reproductive organization is wonderfully unique, so there is no ane size fits all timeframe here.

With that said, ovulation occurs ~36-40 hours afterwards the LH surge is released from the brain. Just the surge that patients detect in urine occurs ~24-36 hours before ovulation actually happens.

How long does the surge final?

Another brilliant question!

An LH surge for most women lasts between 1-3 days, with an upswing toward the surge and a downslope to return to normal baseline levels. So the peak of the surge is shorter, merely the unabridged 'surge process,' from get-go to finish, is generally between ane-2 days.

I meet a pink LH line – am I surging?

Because your torso releases more than and more LH (unremarkably in the morn hours) before the highest peak, y'all could see a very faint LH line taken on bike mean solar day 12, for example, go a pink line on some other OPK (each 'kit' is one examination strip) on day 13, and and so a bright red line on twenty-four hour period 14, followed by a light pink line on mean solar day xv, and no line at all on twenty-four hour period sixteen (which may be the day you really ovulate, considering LH is indicative of impending ovulation, not ovulation itself). This 'curve' was your LH surge – upward, up, peak, downwards, downward.

Just – this curve moves much faster for some women, who could have a pink line in the forenoon and a bright cherry-red line that evening.

LH Surge peak fertility graph and chartThen how often should I be testing?

You lot should be testing once daily, although most women closely tracking their ovulation and LH patterns will rail multiple times a day on the twenty-four hours of an expected surge (subsequently a faint or light pink line indicating the upcoming surge, or vivid scarlet line) to know exactly when they are peaking.

In social club to track correctly, it's crucial to understand your wheel length and usual ovulation day. After tracking your cycle for a few months, you'll know how long it is (the number of days between the commencement of one menses and the outset of the side by side menstruum). Near women ovulate smack dab in the heart of their bicycle, and they can tell because of the type of cervical discharge they accept – clear, 'egg white' discharge commonly accompanies ovulation.

So when should I start testing every month?

Then allow's say you have a 28-twenty-four hour period cycle, and you know from previous OPKs and discharge (and maybe even taking your temperature!) that you ovulate on day 14 of a normal cycle (stress and other factors tin lengthen the duration of your cycle and delay ovulation so keep this in heed if you lot're not seeing an LH surge when you await to).

In this scenario, you should take a daily OPK starting mean solar day 10 and continue until yous see an LH surge (if your ovulation is late you'd miss information technology if you stopped testing on twenty-four hour period 14, when you expected to ovulate). Women with 24-day cycles who ovulate on twenty-four hours x-11 should beginning testing on twenty-four hour period half-dozen until they surge.

Almost women do not ovulate smack dab in the middle of their cycle though. But ~13% of women accept a 28-day bike. Therefore, lots of patients get the timing wrong on when to test, as the surge can and does happen either earlier or after than expected based on a 28-day cycle.

Using a menstruum tracking app similar the 1 built into iPhone iOS is a great mode to get an authentic day of ovulation.

I want to test ofttimes, simply aren't OPKs expensive?

Not all of them! If you buy brand name OPKs from the chemist's, getting many so you can test several times per cycle volition get very expensive. But if yous await around the aisle, you'll see more generic tests offered in bulk that work but besides. Women looking to go even more tests in bulk can look online, where hundreds of working tests can be purchased for a steal.

When is the best time of day to test?

The best time to check LH is late morning through early evening. The LH surge is often released from the brain in the early morning, so if you lot get up early and test your first-morning urine, you lot could miss it. In addition, y'all should subtract fluid intake for ~2 hours prior to ensure that your urine isn't too diluted.

What if I never run across a surge? When should I encounter a fertility specialist?

If yous never come across a surge, don't panic. Information technology's possible your ovulation is delayed due to stress, so your LH superlative is late, as well. In this example, test for several boosted days. Another possibility is that your surge is not meeting the specific LH volume threshold on the OPKs – but this does not mean y'all are not surging or not ovulating!

In this case, you lot may want to wait into low threshold OPKs or go to a fertility medico, or reproductive endocrinologist, who tin can draw your claret to see when you peak (LH is more than accurately measured through blood than urine) and ovulate.

If you really don't call back you are ovulating because you never peak, or are getting all sorts of wonky OPK results (like many peaks days autonomously or a peak every day), you should consider seeing a fertility doctor, too – he or she volition run bloodwork to see what'due south going on and if necessary, prescribe constructive treatment to induce ovulation or achieve pregnancy.

Furthermore, if you are a woman with irregular periods, or y'all know you have PCOS (polycystic ovary syndrome), you are likely to take a difficult time with LH kits and should see a reproductive endocrinologist sooner rather than later.

Can I take ii surges?

While this is rare, some studies suggest it is possible to accept two (or more!) LH peaks, and yes, ovulate more than one time at two split up times in your cycle.

However, the vast majority of fertility doctors and OBGYNs believe that each cycle allows for ane LH surge and i instance of ovulation, and most women who have tested LH every solar day of their cycle would concur!

If you lot are seeing two surges, it might be because your system is nether a blazon of transition, such as with breastfeeding mothers just resuming regular ovulation.

OK, I saw an LH surge. Now what?

Yay! OK, now some more math – since we know ovulation happens 12-48 hours afterward a positive OPK, an ovulated egg lives from 12-24 hours, and sperm lives for every bit long as five days, nosotros tin can say you should definitely have sex as soon as you run into an LH peak and for up to three days afterward. Only y'all can also accept sex the five days leading up to ovulation, and then the mean solar day after ovulation, also.

Overwhelmed? Don't worry – once y'all first tracking, it becomes 2d nature!

Why am I seeing an LH peak during pregnancy?

If you lot took an OPK when your menstruation was a few days late and it showed two red lines, or a surge, congratulations, you are likely pregnant!

Why? Fascinatingly, the pregnancy hormone, Human being Chorionic Gonadotropin, or hCG, and LH share a similar protein structure, so a significant woman who takes an OPK would examination positive – but it's not considering she is virtually to ovulate, it's because she is meaning.

And if you lot're wondering, no, it won't work the other way; a adult female experiencing an LH surge will not become a positive pregnancy test result. That's because hCG is the same protein structure as LH, plus a few other proteins. Cool, right?

And then, OPKs are a good thought?

They are a great thought! While they are not everyone's cup of tea, when paired with knowledge about your menstrual cycle and your cervical belch, they are an first-class – and for most women, indispensable – tool to achieve pregnancy.

It is brash by The American College of Obstetrics and Gynecology that if you are 35 or older and have been trying for vi months to get significant without birth control it is recommended to see a fertility specialist.

While OPKs are a peachy tool to know more than about your menstrual wheel, time may be of the essence, and you may want to seek the aid of a reproductive endocrinologist sooner than yous may think depending on your age.