Postnatal Development

From Embryology
WHO report- child growth standards.jpg


It would seem obvious to say that development does not stop at birth. In fact many systems (cardiovascular, respiratory, gastrointestinal, homeostasis) undergo significant changes at birth, and many others (neural) have not yet completed their development.

Postnatal development can be broadly divided into the age categories of: Neonatal (birth to 1 month), Infancy (1 month to 2 years), Childhood (2 years to puberty), Puberty (12 years to mid-teens) and Young Adult a new category (late teens to early twenties).

Neurological development continues postnatally with both growth and reorganization of the central nervous system. The amount of simple physical growth is shown by the skeletal flexibility designed around the brain and spinal cord, which allows continued postnatal growth of these structures. The World Health Organization (WHO) recently identified early postnatal motor skill development in terms of "motor milestones"[1], this was released along with new international growth charts.

Many factors causing abnormal development can also lead to childhood mortality. In developed countries, we sometimes forget that every year (mainly in developing countries) some 12 million children die before reaching their fifth birthday, many of them during their first year of life. Of these, 70% are killed by one of five causes (diarrhoea, pneumonia, measles, malaria or malnutrition) and often by some combination of them (WHO Fact Sheet N96 November 1995).

For more child population data look at the section below on Child Health Statistics of the world, between and within specific countries.

Note this current project focuses on prenatal development, so postnatal content is not as detailed.

Postnatal Links: birth | neonatal | neonatal diagnosis | milk | Nutrition | growth charts | Disease School Exclusion | vaccination | puberty | genital

Postnatal Neural

The links below are to a set of postnatal Neural Exam Movies by Paul D. Larsen, M.D., University of Nebraska Medical Center.

Newborn normal

Newborn-normal-behaviour.jpg Newborn n 03.jpg Newborn n 17.jpg Newborn n 20.jpg Newborn n 27.jpg
behaviour tone positions reflexes head

Newborn abnormal

Newborn ab 01.jpg Newborn ab 03.jpg Newborn ab 17.jpg Newborn ab 20.jpg Newborn ab 27.jpg
behaviour tone positions reflexes head

Neural Exam Movies


There are many birth and perinatal associated abnormalities. In particular the perinatal period is a time when fetal systems that have either not yet been functional (respiratory, gastrointestinal, neural) or are extensively remodelled (cardiovascular, placental). There are also a number of maternal issues.

The International Classification of Diseases (ICD) has two entire chapters committed to the childbirth and the perinatal period, the major sub-headings are shown below. More detail is available on the chapter pages, Chapter XV Pregnancy Childbirth and Chapter XVI Perinatal Period. The World Health Organization's ICD classification used worldwide as the standard diagnostic tool for epidemiology, health management and clinical purposes. This includes the analysis of the general health situation of population groups. It is used to monitor the incidence and prevalence of diseases and other health problems.

Chapter XV Pregnancy, childbirth and the puerperium (O00-O99)

The codes included in this chapter are to be used for conditions related to or aggravated by the pregnancy, childbirth or by the puerperium (maternal causes or obstetric causes)

Excludes Certain diseases or injuries complicating pregnancy, childbirth and the puerperium classified elsewhere: external causes (for mortality) (V, W, X, Y); injury, poisoning and certain other consequences of external cause (S00-T88.1, , T88.6-T98); mental and behavioural disorders associated with the puerperium (F53.-); obstetrical tetanus (A34); postpartum necrosis of pituitary gland (E23.0); puerperal osteomalacia (M83.0); supervision of high-risk pregnancy (Z35.-); supervision of normal pregnancy (Z34.-).

Chapter XVI Certain conditions originating in the perinatal period (P00-P96)

Includes conditions that have their origin in the perinatal period even though death or morbidity occurs later.

Excludes congenital malformations, deformations and chromosomal abnormalities (Q00-Q99); endocrine, nutritional and metabolic diseases (E00-E90); injury, poisoning and certain other consequences of external causes (S00-T98); neoplasms (C00-D48); tetanus neonatorum (A33)

Major sub-headings are shown below, select the sub-heading link to see details.

Links: XV Pregnancy Childbirth | International Classification of Diseases - XVI Perinatal Period | International Classification of Diseases | Human Abnormal Development




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Cite this page: Hill, M.A. (2020, July 12) Embryology Postnatal Development. Retrieved from

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© Dr Mark Hill 2020, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G