Sex differences in human physiology
Female fertility declines after age 30 and ends with the menopause. Female physical experiences vary depending on external forces such as diet, marriage patterns, culture, and other aspects. In Western nations menstruation begins to affect females at 13 and menopause starts around 51. In non-industrialized countries, on the other hand, most females begin menstruation at a later age. More lactation in the lifetime of non-western females inhibits ovulation and extends the number of fertile years. Pregnancy in the 40s or later has been correlated with increased risk of Down syndrome in the children. Males are capable of fathering children into old age. Paternal age effects in the children include multiple sclerosis, autism, breast cancer and schizophrenia, as well as reduced intelligence. Adriana Iliescu was reported as the world's oldest woman to give birth, at age 66. Her record stood until Maria del Carmen Bousada de Lara gave birth to twin sons at Sant Pau Hospital in Barcelona, Spain on December 29, 2006, at the age of 67. In both cases IVF was used. The oldest known father was former Australian miner Les Colley, who fathered a child at age 93.
Menopause
In younger women, during a normal menstrual cycle the ovaries produce estradiol, testosterone and progesterone in a cyclical pattern under the control of FSH and luteinizing hormone (LH), which are both produced by the pituitary gland. During perimenopause (approaching menopause), estradiol levels and patterns of production remain relatively unchanged or may increase compared to young women, but the cycles become frequently shorter or irregular. The often observed increase in estrogen is presumed to be in response to elevated FSH levels that, in turn, is hypothesized to be caused by decreased feedback by inhibin. Similarly, decreased inhibin feedback after hysterectomy is hypothesized to contribute to increased ovarian stimulation and earlier menopause.