Cerebral palsy

===Preterm birth===
Between 40% and 50% of all children who develop cerebral palsy were born prematurely.<ref name="dev_beh_peds_2009" /> Most of these cases (75–90%) are believed to be due to issues that occur around the time of birth, often just after birth.<ref name="Yar2013" /> Multiple-birth infants are also more likely than single-birth infants to have CP.<ref name="saunders_2011" /> They are also more likely to be born with a [[low birth weight]].<ref>{{Cite journal |last1=Demeši Drljan |first1=Čila |last2=Mikov |first2=Aleksandra |last3=Filipović |first3=Karmela |last4=Tomašević-Todorović |first4=Snežana |last5=Knežević |first5=Aleksandar |last6=Krasnik |first6=Rastislava |date=April 12, 2016 |title=Cerebral palsy in preterm infants |url=https://pubmed.ncbi.nlm.nih.gov/29308865/ |journal=National Library of Medicine |volume=73 |issue=4 |pages=343–348 |doi=10.2298/VSP140321019D |issn=0042-8450 |pmid=29308865}}</ref>

In those who are born with a weight between 1&nbsp;kg (2.2 lbs) and 1.5&nbsp;kg (3.3 lbs) CP occurs in 6%.<ref name="Osk2013" /> Among those born before 28&nbsp;weeks of [[gestation]] it occurs in 8%.<ref name="Osk2016">{{cite journal | vauthors =  | title = Erratum | journal = Developmental Medicine and Child Neurology | volume = 58 | issue = 3 | pages = 316 | date = March 2016 | pmid = 26890023 | doi = 10.1111/dmcn.12662 | s2cid = 221682193 | doi-access = free }}</ref>{{efn|Incorrectly stated as 11% in 2013 <ref name="Osk2013" />}} Genetic factors are believed to play an important role in prematurity and cerebral palsy generally.<ref name="hallman_2012" /> In those who are born between 34 and 37&nbsp;weeks the risk is 0.4% (three times normal).<ref name="poets_2012" />