Editing Intrauterine growth restriction (section)

===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]]