For women in spontaneous labor, contractions are usually two to five minutes apart, last from 30 to 60 seconds, and have moderate strength. The easiest way to assess the power of labor is to time the frequency and duration of the contractions (from the beginning of one to the beginning of the next).
Melatonin, hormone secreted by the pineal gland, a tiny endocrine gland situated at the centre of the brain. Melatonin was first isolated in 1958 by American physician Aaron B. Lerner and his colleagues at Yale University School of Medicine.
The pituitary gland and the hypothalamus, located at the base of the brain, control the production of male hormones and sperm. The hypothalamus makes gonadotropin-releasing hormone (GnRH), which controls the release of other (messenger) hormones from the pituitary gland.