Editing Intrauterine growth restriction (section)

==Types==
There are two major categories of IUGR: pseudo IUGR and true IUGR{{citation needed|date=December 2020}}

With pseudo IUGR, the fetus has a birth weight below the tenth percentile for the corresponding gestational age but has a normal ponderal index, subcutaneous fat deposition, and body proportion. Pseudo IUGR occurs due to uneventful intrauterine course and can be rectified by proper postnatal care and nutrition. Such babies are also called small for gestational age.{{citation needed|date=December 2020}}

True IUGR occurs due to pathological conditions which may be either fetal or maternal in origin. In addition to low body weight they have abnormal ponderal  index, body disproportion, and low subcutaneous fat deposition. There are two types-symmetrical and asymmetrical.<ref name="titleIntrauterine Growth Restriction">{{cite web |url=http://www.obgyn.ufl.edu/ultrasound/MedinfoVersion/sec7/7_3.html |title=Intrauterine Growth Restriction |access-date=2007-11-28 |archive-url=https://web.archive.org/web/20070609035143/http://www.obgyn.ufl.edu/ultrasound/MedinfoVersion/sec7/7_3.html <!-- Bot retrieved archive --> |archive-date=2007-06-09}}</ref><ref name="titleIntrauterine Growth Restriction: Identification and Management - August 1998 - American Academy of Family Physicians">{{cite journal |url=http://www.aafp.org/afp/980800ap/peleg.html |title=Intrauterine Growth Restriction: Identification and Management - August 1998 - American Academy of Family Physicians |journal=American Family Physician |volume=58 |issue=2 |pages=453–60, 466–7 |access-date=2007-11-28 |date=August 1998 |last1=Hunter |first1=Stephen K. |last2=Kennedy |first2=Colleen M. |last3=Peleg |first3=David |pmid=9713399 |archive-date=2011-06-06 |archive-url=https://web.archive.org/web/20110606040232/http://www.aafp.org/afp/980800ap/peleg.html |url-status=dead }}</ref> Some conditions are associated with both symmetrical and asymmetrical growth restriction.{{cn|date=September 2024}}

===Asymmetrical===
Asymmetrical IUGR accounts for 70-80% of all IUGR cases.<ref name=":5" /> In asymmetrical IUGR, there is decreased oxygen or nutrient supply to the fetus during the third trimester of pregnancy due to [[placental insufficiency]].<ref>{{Cite journal|last=Wollmann|first=null|date=1998|title=Intrauterine growth restriction: definition and etiology|url=https://pubmed.ncbi.nlm.nih.gov/9716819|journal=Hormone Research|volume=49|issue=# Suppl 2|pages=1–6|doi=10.1159/000053079|issn=1423-0046|pmid=9716819|s2cid=37436666}}</ref> This type of IUGR is sometimes called "head sparing" because brain growth is typically less affected, resulting in a relatively normal head circumference in these children.<ref name=":6">{{cite journal|last1=Sharma|first1=Deepak|last2=Shastri|first2=Sweta|last3=Farahbakhsh|first3=Nazanin|last4=Sharma|first4=Pradeep|date=December 2016|title=Intrauterine growth restriction - part 1|url=https://pubmed.ncbi.nlm.nih.gov/26856409|journal=The Journal of Maternal-Fetal & Neonatal Medicine|volume=29|issue=24|pages=3977–3987|doi=10.3109/14767058.2016.1152249|issn=1476-4954|pmid=26856409|s2cid=29439634}}</ref> Because of decreased oxygen supply to the fetus, blood is diverted to the vital organs, such as the brain and heart. As a result, blood flow to other organs - including liver, muscle, and fat - is decreased. This causes abdominal circumference in these children to be decreased.<ref name=":6" />

A lack of [[subcutis|subcutaneous fat]] leads to a thin and small body out of proportion with the liver. Normally at birth the brain of the fetus is 3 times the weight of its liver. In IUGR, it becomes 5-6 times. In these cases, the [[embryo]]/fetus has grown normally for the first two [[Pregnancy#Physiology|trimesters]] but encounters difficulties in the third, sometimes secondary to complications such as pre-eclampsia.     Other symptoms than the disproportion include dry, peeling skin and an overly-thin [[umbilical cord]]. The baby is at increased risk of [[Hypoxia (medical)|hypoxia]] and [[hypoglycemia]]. This type of IUGR is most commonly caused by [[extrinsic]] factors that affect the fetus at later gestational ages. Specific causes include:{{citation needed|date=December 2020}}
* Chronic [[high blood pressure]]
* Severe [[malnutrition]]
* Genetic [[mutations]], [[Ehlers–Danlos syndrome]]

===Symmetrical===
Symmetrical IUGR is commonly known as '''global growth restriction''', and indicates that the [[fetus]] has developed slowly throughout the duration of the pregnancy and was thus affected from a very early stage. The head circumference of such a newborn is in proportion to the rest of the body. Since most [[neurons]] are developed by the 18th week of gestation, the fetus with symmetrical IUGR is more likely to have permanent neurological [[sequelae]]. Common causes include:{{citation needed|date=December 2020}}
* Early [[uterus|intrauterine]] infections, such as [[cytomegalovirus]], [[rubella]] or [[toxoplasmosis]]
* [[Chromosome|Chromosomal]] abnormalities
* [[Anemia]]
* Maternal [[Substance abuse|substance use]] (prenatal alcohol use can result in [[Fetal alcohol syndrome]])