Ovulation is the name of the process that happens usually once in every menstrual cycle when hormone changes trigger an ovary to release an egg. You can only become pregnant if a sperm fertilizes an egg. Ovulation usually happens 12 to 16 days before your next period starts.
The eggs are contained in your ovaries. During the first part of each menstrual cycle, one of the eggs is being grown and matured.

What does the LH surge mean for pregnancy?

• As you approach ovulation, your body produces increasing amounts of a hormone called estrogen, which causes the lining of your uterus to thicken and helps create a sperm friendly environment.
• These high estrogen levels trigger a sudden increase in another hormone called luteinising hormone (LH). The ‘LH’ surge causes the release of the mature egg from the ovary – this is ovulation.
• Ovulation normally occurs 24 to 36 hours after the LH surge, which is why the LH surge is a good predictor of peak fertility.

The egg can only be fertilized for up to 24 hours after ovulation. If it isn’t fertilized the lining of the womb is shed (the egg is lost with it) and your period begins. This marks the start of the next menstrual cycle.                                                                            

 What does a surge in LH mean?

The LH surge signals that ovulation is about to start. Ovulation is the medical term for an ovary releasing a mature egg.

A gland in the brain, called the anterior pituitary gland, produces LH.

Levels of LH are low for most of the monthly menstrual cycle. However, around the middle of the cycle, when the developing egg reaches a certain size, LH levels surge to become very high.

A woman is most fertile around this time. People refer to this interval as the fertile window or fertile period.

If there are no complications affecting fertility, having sex several times within the fertile period may be enough to conceive.

The LH surge begins around 36 hoursTrusted Source before ovulation. Once the egg is released, it survives for about 24 hours, after which time the fertile window is over.

Because the period of fertility is so short, it is important to keep track of it when trying to conceive, and noting the timing of the LH surge can help.

Diagnostic Kit for Luteinizing Hormone (fluorescence immunochromatographic assay) is a fluorescence immunochromatographic assay for the quantitative detection of Luteinizing Hormone (LH) in human serum or plasma, which is mainly used in the evaluation of pituitary endocrine function.