title: Factors associated with small head circumference at birth among infants born before the 28th week.
abstract: OBJECTIVE
  We sought to identify risk factors for congenital microcephaly in extremely low gestational age newborns.
  
  
  METHODS
  Demographic, clinical, and placental characteristics of 1445 infants born before the 28th week were gathered and evaluated for their relationship with congenital microcephaly.
  
  
  RESULTS
  Almost 10% of newborns (n = 138), rather than the expected 2.2%, had microcephaly defined as a head circumference >2 SD below the median. In multivariable models, microcephaly was associated with nonwhite race, severe intrauterine growth restriction, delivery for preeclampsia, placental infarction, and being female. The risk factors for a head circumference between <1 and >2 SD below the median were similar to those of microcephaly.
  
  
  CONCLUSIONS
  Characteristics associated with fetal growth restriction and preeclampsia are among the strongest correlates of microcephaly among children born at extremely low gestational ages. The elevated risk of a small head among nonwhites and females might reflect the lack of appropriate head circumference standards.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Thomas F
authors.initials: TF
authors.lastname: McElrath
authors.forename: Elizabeth N
authors.initials: EN
authors.lastname: Allred
authors.forename: Karl
authors.initials: K
authors.lastname: Kuban
authors.forename: Jonathan L
authors.initials: JL
authors.lastname: Hecht
authors.forename: Andrew
authors.initials: A
authors.lastname: Onderdonk
authors.forename: T Michael
authors.initials: TM
authors.lastname: O'Shea
authors.forename: Nigel
authors.initials: N
authors.lastname: Paneth
authors.forename: Alan
authors.initials: A
authors.lastname: Leviton
mesh_terms: D002508:Cephalometry; D002657:Child Development / Q000502:physiology; D036861:Delivery, Obstetric / Q000379:methods; D005260:Female; D005317:Fetal Growth Retardation / Q000175:diagnosis* / Q000453:epidemiology; D005500:Follow-Up Studies; D005865:Gestational Age; D006257:Head / Q000254:growth & development; D006801:Humans; D007226:Infant Mortality / Q000639:trends; D052577:Infant, Extremely Low Birth Weight; D007231:Infant, Newborn; D007234:Infant, Premature; D008831:Microcephaly / Q000175:diagnosis* / Q000453:epidemiology*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D018570:Risk Assessment