title: Effect of interpregnancy interval on adverse perinatal outcomes--a national study.
abstract: BACKGROUND
  The interpregnancy interval (IPI) has been reported to influence the outcome of pregnancy and birth. We performed a national study in Israel to determine the impact of IPI on multiple adverse perinatal outcomes.
  
  
  METHODS
  This longitudinal cohort study used birth certificates of siblings born to the same biological mother, with at least one previous birth and a subsequent singleton pregnancy. Adverse pregnancy outcomes included preterm delivery, very preterm birth, small for gestational age (SGA), very SGA (VSGA), early neonatal death and major congenital malformations. Multivariate logistic regression was performed for each outcome.
  
  
  RESULTS
  The study included 440,838 of a total of 846,845 reported live births in Israel over 5 years; excluded were primiparas (32%), multifetal births (4.9%) and those with incomplete data (10.9%). For IPIs shorter than 6 months, there were significantly increased risks for preterm birth (OR=1.23), SGA (OR=1.14), VSGA (OR=1.15), early neonatal death (OR=1.62) and congenital malformations (OR=1.14). Intervals of 60 months or longer had higher risks for preterm birth (OR=1.39) and VSGA (OR=1.16).
  
  
  CONCLUSIONS
  Optimal IPI recommendation of >11 months is an accessible and low-cost means to improve multiple adverse perinatal outcomes.
authors.affiliation: Department of Obstetrics and Gynecology, Shaare Zedek Medical Center, Jerusalem 91031, Israel. granovs@012.net.il
authors.forename: Sorina
authors.initials: S
authors.lastname: Grisaru-Granovsky
authors.forename: Ethel-Sherry
authors.initials: ES
authors.lastname: Gordon
authors.forename: Ziona
authors.initials: Z
authors.lastname: Haklai
authors.forename: Arnon
authors.initials: A
authors.lastname: Samueloff
authors.forename: Michael M
authors.initials: MM
authors.lastname: Schimmel
mesh_terms: D001719:Birth Certificates; D001721:Birth Intervals; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D007557:Israel; D008137:Longitudinal Studies; D008297:Male; D008423:Maternal Age; D015999:Multivariate Analysis; D016017:Odds Ratio; D010298:Parity; D011247:Pregnancy; D011256:Pregnancy Outcome; D047928:Premature Birth; D011446:Prospective Studies; D012044:Regression Analysis; D012307:Risk Factors