LH (Luteinising Hormone) Surge

To increase your chances in getting pregnant, you need to pinpoint your ovulation period accurately.

To do that, you need to know when your LH surge would occur.

Here’s what you need to know about it:

What Is LH Surge?

In menstrual cycle, the body begins to produce follicle stimulating hormone (FSH). FSH facilitates the formation of a follicle on one of the ovaries. The follicle contains and nurtures the egg. When a follicle has adequately matured, a surge of luteinising hormone (LH) causes the follicle to burst and release the egg into the fallopian tube causing ovulation. The egg travels down the fallopian tubes towards the uterus. At this point, fertilisation of the egg may take place and increases your chances of getting pregnant.

A woman experiences the LH surge somewhere between the12th and 16th day of her menstrual cycle. When the LH surge happens, meiosis (the process of cell division which decreases a cell’s chromosomes by half) is resumed in the cells of the ovaries. Meiosis is a necessary process to allow the egg to unite with sperm (which also undergoes meiosis) and still maintain the correct amount of chromosomes.

Relevance Of LH Surge To Ovulation

Ovulation is the most fertile period of a woman’s cycle; this is the woman’s best time to try when attempting conception. Learning how a woman ovulates can give you a deeper understanding of your body functions and help in getting pregnant.

Prior to ovulation, women experience an “LH surge” a sudden, dramatic, and brief rise in the level of luteinising hormone. Ovulation tests detect this LH surge, allowing you to accurately predict when you will ovulate. Ovulation occurs approximately 10-12 hours after the LH peak. A positive result on an ovulation test means that the woman will most likely become fertile over the next three days with peak fertility at 36 hours following the LH surge.

LH Surge And Ovulation Testing

Ovulation tests identify luteinising hormone (LH) – an ovulation predictor. High levels of LH cause a woman to ovulate (egg bursts from the ovarian follicle – fertile period). Most women will ovulate within 24-36 hours after a short-lived LH surge inside her body; therefore detecting LH by a fertility test is an effective method in anticipating a fertile period.

Statistically, there are 5 fertile days in a woman’s cycle which can be determined by the following:

  • 3 days prior to ovulation, spermatozoa can survive in the female body for up to 72 hours. For that reason, sexual intercourse even up to 3 days prior to ovulation can lead to a pregnancy and 2 days of actual ovulation.
  • If no or only protected sexual intercourse takes place during this time, a pregnancy is likely to occur.

When To Take An Ovulation Test?

The LH surge is, very short and for you to detect the LH surge you need to test at the right time of the month and the right time of day. As LH is produced by the body in the morning, mid-afternoon is considered the ideal time to test.

  1. Determine your cycle length (the number of days from the first day of menstruation to the day before the menstrual bleeding begins on the next menstrual period).
  2. If you don’t know your regular cycle length, you may start testing 9 days after the first day of your menstruation. The average cycle length of a woman is 28 days.
  3. Perform the ovulation detection each day within a five-day period or until the luteinising hormone surge has been identified.

Other Ways To Pinpoint Ovulation

You can also try other ways to pinpoint your time of ovulation such as:

Since this ovulation “window” only opens once every month (and the unfertilised egg has a short 24-hour life-span) predicting ovulation accurately can be helpful when trying to become pregnant. Therefore, you should have sex over the next 48 hours after the LH surge is detected.

Ovulation home kit is a tool for fertility testing that pins down the surge of luteinising hormone and foresee ovulation – the most fertile time in a woman’s monthly cycle. This tool must not be mistaken as a way to improve your chances of success in getting yourself pregnant. The best way to conceive is regular sexual intercourse throughout the cycle. Ovulation detection is also useful if:

  • The woman has an irregular cycle that makes it more difficult to get pregnant.
  • You suspect that you are not ovulating and decide to make a test first in your own home before going to a fertility clinic.
  • One or both partners frequently work away from home and schedules sexual intercourse during a fertile period.
  • Caring for existing children that makes sex a less priority.
  • You don’t want to get pregnant by avoiding this fertile period of your cycle.


  • Follow all the instructions written in the pouch before performing the test.
  • Do not open the protective pouch until you are ready to perform the test.
  • Store the test at room temperature.
  • Check the expiration date.
  • Do not re-use.
  • Keep out of reach of children.

LH Surge And Hormones

During ovulation, several hormones inside a woman?s body are synchronised to prepare the woman for ovulation, fertilisation and implantation.

Gonadotropin-releasing hormone (GnRH) – released by the hypothalamus (a part of the brain) and stimulates the release of follicle-stimulating hormone (FSH) and luteinising hormone (LH) from the pituitary gland.

Follicle Stimulating Hormone (FSH) – released by the pituitary gland and stimulates the growth of follicles in the ovaries, (a follicle is a balloon shaped structure which is filled with fluid and contains an egg, follicles are found in the ovaries) to ripen several eggs and secretes estrogen.

Lutenising hormone (LH) – produced by the pituitary gland. It helps in the development of the follicles, and works with the FSH that triggers ovulation and stimulates production of other hormones necessary for the post ovulatory stage of the menstrual cycle – estrogen and progesterone.

Estrogen – It is a hormone secreted by the ovarian follicles and the corpus luteum which stimulates thickening of the uterine wall, maturation of an egg, and development of female sex characteristics. Also provides feedback to inhibit FSH secretion and increase LH secretion.

Progesterone – hormone secreted by the corpus luteum that stimulates thickening of the uterine wall and formation of mammary ducts.

Understanding the process of ovulation and your particular reproductive cycle can help you plan your pregnancy more effectively.

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