title: A large head circumference is more strongly associated with unplanned cesarean or instrumental delivery and neonatal complications than high birthweight.
abstract: OBJECTIVE
  Fetal size impacts on perinatal outcomes. We queried whether the fetal head, as the fetal part interfacing with the birth canal, might impact on obstetric outcomes more than birthweight (BW). We examined associations between neonatal head circumference (HC) and delivery mode and risk of perinatal complications as compared to high BW.
  
  
  METHODS
  This was an electronic medical records-based study of term singleton births (37-42 weeks' gestation) from January 2010 through December 2012 (N = 24,780, 6343 primiparae). We assessed risks of unplanned cesarean or instrumental delivery and maternal and fetal complications in cases with HC or BW ≥95th centile (large HC, high BW) vs those with parameters <95th centile (normal). Newborns were stratified into 4 subgroups: normal HC/normal BW (reference, n = 22,548, primiparae 5862); normal HC/high BW (n = 817, P = 213); large HC/normal BW (n = 878, P = 265); and large HC/high BW (n = 537, P = 103). Multinomial multivariable regression provided adjusted odds ratio (aOR) while controlling for potential confounders.
  
  
  RESULTS
  Infants with HC ≥95th centile (n = 1415) were delivered vaginally in 62% of cases, unplanned cesarean delivery 16%, and instrumental delivery 11.2%; 78.4% of infants with HC <95th centile were delivered vaginally, 7.8% unplanned cesarean, and 6.7% instrumental delivery. Odds ratio (OR) for unplanned cesarean was 2.58 (95% confidence interval [CI], 2.22-3.01) and for instrumental delivery OR was 2.13 (95% CI, 1.78-2.54). In contrast, in those with BW ≥95th centile (n = 1354) 80.3% delivered vaginally, 10.2% by unplanned cesarean (OR, 1.2; 95% CI, 1.01-1.44), and 3.4% instrumental delivery (OR, 0.46; 95% CI, 0.34-0.62) compared to infants with BW <95th centile: spontaneous vaginal delivery, 77.3%, unplanned cesarean 8.2%, instrumental 7.1%. Multinomial regression with normal HC/normal BW as reference group showed large HC/normal BW infants were more likely to be delivered by unplanned cesarean (aOR, 3.08; 95% CI, 2.52-3.75) and instrumental delivery (aOR, 3.03; 95% CI, 2.46-3.75). Associations were strengthened in primiparae. Normal HC/high BW was not associated with unplanned cesarean (aOR, 1.18; 95% CI, 0.91-1.54), while large HC/high BW was (aOR, 1.93; 95% CI, 1.47-2.52). Analysis of unplanned cesarean indications showed large HC infants had more failure to progress (27.7% vs 14.1%, P < .001), while smaller HC infants had more fetal distress (23.4% vs 16.9%, P < .05).
  
  
  CONCLUSIONS
  A large HC is more strongly associated with unplanned cesarean and instrumental delivery than high BW. Prospective studies are needed to test fetal HC as a predictive parameter for prelabor counseling of women with "big babies."
authors.affiliation: Division of Obstetrics and Gynecology, Hadassah-Hebrew University Medical Centers Jerusalem, Jerusalem, Israel.
authors.forename: Michal
authors.initials: M
authors.lastname: Lipschuetz
authors.affiliation: Division of Obstetrics and Gynecology, Hadassah-Hebrew University Medical Centers Jerusalem, Jerusalem, Israel.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Cohen
authors.affiliation: Division of Obstetrics and Gynecology, Hadassah-Hebrew University Medical Centers Jerusalem, Jerusalem, Israel; Faculty of Medicine of the Hebrew University and Hadassah, Braun School of Public Health and Community Medicine, Jerusalem, Israel.
authors.forename: Eliana
authors.initials: E
authors.lastname: Ein-Mor
authors.affiliation: Division of Obstetrics and Gynecology, Hadassah-Hebrew University Medical Centers Jerusalem, Jerusalem, Israel.
authors.forename: Hanna
authors.initials: H
authors.lastname: Sapir
authors.affiliation: Division of Obstetrics and Gynecology, Hadassah-Hebrew University Medical Centers Jerusalem, Jerusalem, Israel.
authors.forename: Drorith
authors.initials: D
authors.lastname: Hochner-Celnikier
authors.affiliation: Division of Obstetrics and Gynecology, Hadassah-Hebrew University Medical Centers Jerusalem, Jerusalem, Israel.
authors.forename: Shay
authors.initials: S
authors.lastname: Porat
authors.affiliation: Division of Obstetrics and Gynecology, Hadassah-Hebrew University Medical Centers Jerusalem, Jerusalem, Israel.
authors.forename: Hagai
authors.initials: H
authors.lastname: Amsalem
authors.affiliation: Division of Obstetrics and Gynecology, Hadassah-Hebrew University Medical Centers Jerusalem, Jerusalem, Israel.
authors.forename: Dan V
authors.initials: DV
authors.lastname: Valsky
authors.affiliation: Division of Obstetrics and Gynecology, Hadassah-Hebrew University Medical Centers Jerusalem, Jerusalem, Israel.
authors.forename: Yossef
authors.initials: Y
authors.lastname: Ezra
authors.affiliation: Division of Obstetrics and Gynecology, Hadassah-Hebrew University Medical Centers Jerusalem, Jerusalem, Israel.
authors.forename: Matan
authors.initials: M
authors.lastname: Elami-Suzin
authors.affiliation: Faculty of Medicine of the Hebrew University and Hadassah, Braun School of Public Health and Community Medicine, Jerusalem, Israel.
authors.forename: Ora
authors.initials: O
authors.lastname: Paltiel
authors.affiliation: Division of Obstetrics and Gynecology, Hadassah-Hebrew University Medical Centers Jerusalem, Jerusalem, Israel. Electronic address: simcha.yagel@gmail.com.
authors.forename: Simcha
authors.initials: S
authors.lastname: Yagel
mesh_terms: D000328:Adult; D001724:Birth Weight; D002508:Cephalometry; D002585:Cesarean Section; D003430:Cross-Sectional Studies; D004630:Emergencies; D005113:Extraction, Obstetrical; D005183:Failure to Thrive / Q000453:epidemiology; D005260:Female; D005316:Fetal Distress / Q000453:epidemiology; D005320:Fetal Macrosomia / Q000453:epidemiology; D005333:Fetus / Q000033:anatomy & histology*; D006257:Head / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D007231:Infant, Newborn; D007557:Israel / Q000453:epidemiology; D008297:Male; D015999:Multivariate Analysis; D010298:Parity; D011247:Pregnancy; D014463:Ultrasonography
keywords: birthweight; head circumference; instrumental delivery; unplanned cesarean delivery