page_title: Luteinizing hormone
section_title: Predicting ovulation
hierarchical_section_title: Luteinizing hormone / Predicting ovulation
caption_attribution_description: English: Chance of fertilization by menstrual cycle day relative to ovulation, with data from two different studies. Reference: &#32;(1999).&#32;"Day-specific probabilities of clinical pregnancy based on two studies with imperfect measures of ovulation". Human Reproduction&#32;14&#32;(7): 1835–1839. DOI:10.1093/humrep/14.7.1835. ISSN 1460-2350.
context_page_description: Luteinizing hormone is a hormone produced by gonadotropic cells in the anterior pituitary gland. In females, an acute rise of LH triggers ovulation and development of the corpus luteum. In males, where LH had also been called interstitial cell–stimulating hormone, it stimulates Leydig cell production of testosterone. It acts synergistically with follicle-stimulating hormone.
context_section_description: The detection of a surge in release of luteinizing hormone indicates impending ovulation. LH can be detected by urinary ovulation predictor kits (OPK, also LH-kit) that are performed, typically daily, around the time ovulation may be expected.  A conversion from a negative to a positive reading would suggest that ovulation is about to occur within 24–48 hours, giving women two days to engage in sexual intercourse or artificial insemination with the intention of conceiving. 
  The recommended testing frequency differs between manufacturers. For example, the Clearblue test is taken daily, and an increased frequency does not decrease the risk of missing an LH surge. On the other hand, the Chinese company Nantong Egens Biotechnology recommends using their test twice per day. If testing once per day, no significant difference has been found between testing LH in the morning versus in the evening, in relation to conception rates, and recommendations of what time in the day to take the test varies between manufacturers and healthcare workers. Tests may be read manually using a color-change paper strip, or digitally with the assistance of reading electronics.
  Tests for luteinizing hormone may be combined with testing for estradiol in tests such as the Clearblue fertility monitor.
  The sensitivity of LH tests are measured in milli international unit, with tests commonly available in the range 10–40 m.i.u. (the lower the number, the higher the sensitivity).
  As sperm can stay viable in the woman for several days, LH tests are not recommended for contraceptive practices, as the LH surge typically occurs after the beginning of the fertile window.
caption: Chance of fertilization by menstrual cycle day relative to ovulation.[19]
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