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Development before birth, or prenatal development (from Latin natalis ' relating to birth ') is the process in which a zygote, and later an embryo, and then a fetus develops during gestation. Prenatal development starts with fertilization and the formation of the zygote , the first stage in embryonic development which continues in fetal ...
Premature birth is the leading cause of death in children under five years of age though many that survive experience disabilities including learning defects and visual and hearing problems. Causes for early birth may be unknown or may be related to certain chronic conditions such as diabetes, infections, and other known causes.
This is an accepted version of this page This is the latest accepted revision, reviewed on 16 February 2025. Person's acquisition of United States citizenship by virtue of the circumstances of birth For laws regarding U.S. citizenship, see United States nationality law. For U.S. citizenship (birthright and naturalized), see Citizenship of the United States. United States citizenship and ...
Birth is the act or process of bearing or bringing forth offspring, [1] also referred to in technical contexts as parturition. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the fetus at a developmental stage when it is ready to feed and breathe.
In order for human reproduction to be achieved, an individual must have undergone puberty first, requiring ovulation in females and the spermarche in males to have occurred prior to engaging in sexual intercourse or achieving pregnancy through non-penetrative means.
The speed of physical growth is rapid in the months after birth, then slows, so birth weight is doubled in the first four months, tripled by 1 year, but not quadrupled until 2 years. [85] Growth then proceeds at a slow rate until a period of rapid growth occurs shortly before puberty (between about 9 and 15 years of age). [ 86 ]
The women would usually return to China within one to two months of giving birth. While pregnant individuals can visit the U.S., Customs and Border Protection on its website notes that officers ...
Organogenesis is the development of the organs that begins during the third to eighth week, and continues until birth. Sometimes full development, as in the lungs, continues after birth. Different organs take part in the development of the many organ systems of the body.