title: Male fetal sex is associated with earlier onset of placental abruption.
abstract: OBJECTIVE
  Placental abruption is an important cause of preterm birth, and perinatal morbidity and mortality. Although more common with male fetuses, outcomes have not been evaluated by sex. Our aim was to find out whether short-term morbidity differs by infant sex in cases with placental abruption and in controls.
  
  
  METHODS
  Register-based case-control study.
  
  
  METHODS
  National Hospital Discharge Register and Medical Birth Register data 1987-2005.
  
  
  METHODS
  The study population consisted of 4,081 women with placental abruption and singleton infant. Three control women without placental abruption were selected for each case matched by maternal age, parity, year of birth, and hospital district. A total of 3,688 cases and 12,695 controls had liveborn infants.
  
  
  METHODS
  Data on pregnancy, delivery, and perinatal outcomes were collected.
  
  
  METHODS
  Placental abruption.
  
  
  RESULTS
  The sex ratio (proportion of male) of cases was 0.548 and of controls 0.516 (p = 0.001). Compared with females, male fetuses in the placental abruption group were born earlier (p = 0.018). Compared with controls, cases with placental abruption were born earlier (p < 0.001), had lower birthweight (p < 0.001), were more often growth restricted (p < 0.001), had lower Apgar scores (p < 0.001) and pH (p < 0.001). Newborn cases needed special care, respirator treatment, antimicrobial and phototherapy more often (p < 0.001) than controls. There was no difference in perinatal outcomes between female and male infants in the placental abruption group.
  
  
  CONCLUSIONS
  Placental abruption occurred earlier in pregnancy with male fetal sex but otherwise the outcomes were similar. Compared with controls newborns in the placental abruption group had a worse outcome.
authors.affiliation: Department of Obstetrics and Gynecology, University Central Hospital, Helsinki, Finland. minna.tikkanen@hus.fi
authors.forename: Minna
authors.initials: M
authors.lastname: Tikkanen
authors.forename: Marjo
authors.initials: M
authors.lastname: Metsäranta
authors.forename: Mika
authors.initials: M
authors.lastname: Gissler
authors.forename: Tiina
authors.initials: T
authors.lastname: Luukkaala
authors.forename: Vilho
authors.initials: V
authors.lastname: Hiilesmaa
authors.forename: Olavi
authors.initials: O
authors.lastname: Ylikorkala
authors.forename: Jorma
authors.initials: J
authors.lastname: Paavonen
authors.forename: Sture
authors.initials: S
authors.lastname: Andersson
authors.forename: Mika
authors.initials: M
authors.lastname: Nuutila
mesh_terms: D000037:Abruptio Placentae / Q000453:epidemiology* / Q000209:etiology; D001034:Apgar Score; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D005260:Female; D005387:Finland / Q000453:epidemiology; D005865:Gestational Age; D006801:Humans; D007226:Infant Mortality / Q000639:trends; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007745:Labor Onset; D008297:Male; D008423:Maternal Age; D010298:Parity; D011247:Pregnancy; D011256:Pregnancy Outcome; D047928:Premature Birth / Q000453:epidemiology*; D011336:Probability; D012016:Reference Values; D012042:Registries; D018570:Risk Assessment; D012737:Sex Factors; D018709:Statistics, Nonparametric; D013997:Time Factors