ClientBlogWhat is an LH Surge and how can it help you conceive?
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What is an LH Surge and how can it help you conceive?

What is LH Surge? Cryos explains

Many potential parents have done extensive research in order to find the best methods to increase their odds of conception. Tracking ovulation is one great tool to use in order to improve your chances of getting pregnant. Knowing when your Luteinizing Hormone (LH) surge usually occurs can help you track when you're ovulating, however, many people are unsure what an LH surge is.

Cryos wants to make sure that your path to parenthood is as simple as possible. We've created a guide below to help you understand what an LH surge is and help you identify when it's coming.

What is the Luteinizing Hormone or LH Surge?

The LH surge is an important part of your menstrual cycle. During your menstrual cycle, the pituitary gland secretes Luteinizing Hormones at low levels. However, once an egg reaches a certain stage of development the body rapidly increases the levels of Lutenizing Hormone produced. This increase called LH surge is what triggers ovulation, which happens 24 to 36 hours later.

Once an egg is released, a structure known as the corpus luteum is formed from the follicle. The corpus luteum secretes a chemical called progesterone which is needed to support a pregnancy. If pregnancy does not occur, the corpus luteum will shrivel up and will stop the progesterone production. Once the progesterone secretion stops a menstrual period is triggered. Keep in mind that an LH surge does not always guarantee that a successful ovulation will occur.

Why is tracking your LH Surge important?

The time that you have to conceive is often shorter than you may think. The fertile window for a woman, which is the window of time a woman can get pregnant is typically 6 days. With frozen sperm, which can survive up to 72 hours the fertile window will decrease a bit. However, frozen sperm can be thawed and inseminated whenever the woman is in her fertile window. This article posted by the University of California San Francisco, says fresh sperm cells can survive up to 5 days inside a woman's reproductive organs.

According to, a woman's egg can only live up to 24 hours after ovulation. The fertile window is a combination of the length of time the sperm cells survive  and the amount of time a woman's egg can survive after ovulation. Ovulation typically occurs 24 to 36 hours after an LH surge. Therefore, tracking your LH surge can help you plan your insemination when your fertility is at its peak.

This is why it is so important to track your ovulation for several months before you begin trying to conceive (TTC).

Illustration of the menstrual cycle

Illustration of the menstrual cycle

How do you track when your LH Surge will occur?

An ovulation predictor kit (OPK) is a tool that women can use to help determine when they will have an LH surge. You can buy OPKs without a prescription, and they are available for purchase online or in most pharmacies or big box stores.

OPKs measure the Lutenizing Hormone levels in urine, by analyzing the urine left from peeing on the stick. The OPK test will yield either a positive or negative result. A positive result indicates that you have a high amount of Lutenizing Hormone in your system. Once ovulation has ended the Lutenizing Hormone level in your system drops, so the OPK will only yield a positive result during your most fertile time.

It is recommended that you read the instructions on an OPK carefully, as most have different steps you need to take in order for them to work properly.

Women with certain medical conditions or those approaching menopause may have elevated levels of LH in their system. In this case, a better option than an OPK test is a blood test which is a more reliable testing option for women who are in this demographic.

What should you take away from all this?

An LH Surge is the 24 to 36 hour time frame before ovulation begins. It is during this time that women are the most fertile and have the highest chance of becoming pregnant. Using tools such as an ovulation predictor kit or blood tests can help you determine when your LH surge is occurring.

Contact Cryos

If you want to learn more about women’s fertility and eggs, following this link to our blog post on the subject.

If you have any questions or would like additional information, please contact us. Our Customer Care Team is ready to help you via phone at +1 (407) 203 1175, via e-mail at [email protected], or via live chat on our website.

Cryos is here to help you make your family dreams become a reality!