Perinatal period

Perinatal period

Perinatal defines the period occurring "around the time of birth", specifically from 22 completed weeks (154 days) of gestation (the time when birth weight is normally 500 g) to seven completed days after birth. ^[10]

Legal regulations in different countries include gestation age beginning from 16 - 22 weeks (5 months) before birth.

This article is about prenatal development in humans. For other species, see prenatal development (non-human).

"Unborn child" redirects here; for other uses, see unborn child (disambiguation).

Prenatal or antenatal development is the process in which an embryo or fetus (or foetus) gestates during pregnancy, from fertilization until birth. Often, the terms fetal development, foetal development, or embryology are used in a similar sense.

After fertilization the embryogenesis starts. In humans, when embryogenesis finishes, by the end of the 10th week of gestational age, the precursors of all the major organs of the body have been created. Therefore, the following period, the fetal period, is described both topically on one hand, i.e. by organ, and strictly chronologically on the other, by a list of major occurrences by weeks of gestational age.

Postnatal period

Postnatal (Latin for 'after birth', from post meaning "after" and natalis meaning "of birth") is the period beginning immediately after the birth of a child and extending for about six weeks. A more correct^{[citation needed]} term would be postpartum period, as it refers to the mother (whereas postnatal refers to the infant). Less frequently used is puerperium.

Biologically, it is the time after birth, a time in which the mother's body, including hormone levels and uterus size, return to prepregnancy conditions. Lochia is post-partum vaginal discharge, containing blood, mucus, and placental tissue.

During the first stages of this period, the newborn also starts his/her adaptation to extrauterine life, the most significant^{[citation needed]} physiological transition until death.

In scientific literature the term is commonly abbreviated to PX. So that 'day P5' should be read as 'the fifth day after birth'.