Search results
Results from the WOW.Com Content Network
Menstruation (also called menstrual bleeding, menses or a period) is the first and most evident phase of the uterine cycle and first occurs at puberty. Called menarche, the first period occurs at the age of around twelve or thirteen years. [8] The average age is generally later in the developing world and earlier in the developed world. [42]
The first day of menstrual bleeding is the date used for the last menstrual period (LMP). The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women, and 21 to 35 days in adults. [2] [3] The average length is 28 days; one study estimated it at 29.3 days. [10]
t. e. Menarche (/ məˈnɑːrki / mə-NAR-kee; from Ancient Greek μήν (mēn) 'month' and ἀρχή (arkhē) 'beginning') is the first menstrual cycle, or first menstrual bleeding, in female humans. From both social and medical perspectives, it is often considered the central event of female puberty, as it signals the possibility of fertility.
The findings, published May 29 in JAMA Network Open, indicate the average age at menarche — an individual’s first period — decreased from 12.5 years for those born 1950–1969 to 11.9 years ...
Human pregnancy can be divided into three trimesters, each approximately three months long: the first, second, and third trimester. The first trimester is from the last menstrual period through the 13th week, the second trimester is 14th–28/29th week, and the third trimester is 29/30th–42nd week. [ 6 ]
The Renaissance (UK: / rəˈneɪsəns / rən-AY-sənss, US: / ˈrɛnəsɑːns / ⓘ REN-ə-sahnss) [1][2][a] is a period of history and a European cultural movement covering the 15th and 16th centuries. It marked the transition from the Middle Ages to modernity and was characterized by an effort to revive and surpass the ideas and achievements ...
The timeline of human evolution outlines the major events in the evolutionary lineage of the modern human species, Homo sapiens, throughout the history of life, beginning some 4 billion years ago down to recent evolution within H. sapiens during and since the Last Glacial Period. It includes brief explanations of the various taxonomic ranks in ...
Trilobites first appeared during the Cambrian period and were among the most widespread and diverse groups of Paleozoic organisms. The rate of the evolution of life as recorded by fossils accelerated in the Cambrian period (542–488 Ma). [21] The sudden emergence of many new species, phyla, and forms in this period is called the Cambrian ...