title: Relationship between interpregnancy interval and cervical length in high-risk women.
abstract: OBJECTIVE
  Our objective was to evaluate the relationship between the interpregnancy interval (IPI) and next-pregnancy mid-trimester cervical length (CL) in women at high risk for recurrent spontaneous preterm birth (SPTB).
  
  
  METHODS
  Retrospective review identified high-risk women, defined as a prior SPTB <36 weeks, who began scheduled serial transvaginal sonographic CL screening at 16-18 weeks gestation between December 2008 and November 2010. All CL assessment ended by 22(6/7) weeks, and weekly 17-α hydroxyprogesterone caproate, 250 mg IM, was recommended to all patients. Details of the prior and current pregnancy were collected, and regression models were used to evaluate the relationship between IPI and CL shortening.
  
  
  RESULTS
  One hundred and eight women with singleton gestations and a qualifying SPTB underwent CL screening. The mean (SD) birth gestational age (GA) of the last pregnancy was 25 (10) weeks, the median IPI was 613 (range 49-6038) days, and the mean (SD) delivery GA in the current pregnancy was 36 (5.3) weeks. Linear regression found no significant relationship between the IPI and the GA of the current birth (p = 0.98). There was a weak significant relationship between IPI and shortest CL (p = 0.04). However, after controlling for the GA of the prior pregnancy, this relationship was non-significant (p = 0.13).
  
  
  CONCLUSIONS
  IPI does not predict next birth outcome or next-pregnancy mid-trimester CL in high-risk women managed with progesterone and ultrasound-indicated cerclage.
authors.affiliation: a Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology , University of Alabama at Birmingham , Birmingham, AL , USA.
authors.forename: Akila
authors.initials: A
authors.lastname: Subramaniam
authors.affiliation: a Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology , University of Alabama at Birmingham , Birmingham, AL , USA.
authors.forename: Luisa L
authors.initials: LL
authors.lastname: Wetta
authors.affiliation: a Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology , University of Alabama at Birmingham , Birmingham, AL , USA.
authors.forename: John
authors.initials: J
authors.lastname: Owen
mesh_terms: D000077713:17 alpha-Hydroxyprogesterone Caproate; D000328:Adult; D001721:Birth Intervals; D023802:Cerclage, Cervical; D054791:Cervical Length Measurement; D005260:Female; D005865:Gestational Age; D006801:Humans; D006908:Hydroxyprogesterones / Q000627:therapeutic use; D016014:Linear Models; D011247:Pregnancy; D047928:Premature Birth / Q000517:prevention & control*; D011372:Progestins / Q000627:therapeutic use; D012189:Retrospective Studies
chemical_list: D006908:Hydroxyprogesterones; D011372:Progestins; D000077713:17 alpha-Hydroxyprogesterone Caproate
keywords: Cervical length; high-risk women; interpregnancy interval