title: Effect of 17-alpha hydroxyprogesterone caproate on cervical length in twin pregnancies.
abstract: OBJECTIVE
  Previous studies on singleton pregnancies have indicated that progestogens may reduce the rate of cervical shortening during pregnancy. The aim of this study was to investigate whether treatment with 17-alpha hydroxyprogesterone caproate (17-OHPC) has an effect on cervical shortening in twin pregnancies.
  
  
  METHODS
  This was a secondary analysis of patients who had participated in a multicenter randomized clinical trial on the effectiveness of 17-OHPC in preventing preterm birth in multiple pregnancies (the AMPHIA-trial). We included all trial participants with a twin gestation who had undergone repeat cervical length measurements during pregnancy. We performed a separate analysis of women with repeat measurements in centers where this was standard protocol for multiple pregnancies. The rate of cervical shortening for both the 17-OHPC group and the placebo group was analyzed using a linear mixed model.
  
  
  RESULTS
  Of the 671 patients who participated in the trial, 282 (42%) had a twin pregnancy and underwent two or more cervical length measurements. Of these women, 140 were monitored in centers where repeat measurements were standard protocol. We observed an overall reduction of cervical length from 44.3 mm at 14-18 weeks to 30.0 mm at 30-34 weeks' gestation. In the 17-OHPC group, cervical length decreased by 1.04 mm each gestational week, while this was 1.11 mm per week for the placebo group (P = 0.6). For the overall group, each 10% decrease in cervical length led to an increase in the risk of preterm birth (hazard ratio, 1.14; 95% CI, 1.08-1.21).
  
  
  CONCLUSIONS
  In women with a twin pregnancy, there is progressive shortening of the cervix during pregnancy, regardless of 17-OHPC use.
authors.affiliation: Department of Obstetrics and Gynaecology, Academic Medical Center, Amsterdam, The Netherlands. A.C.Lim@amc.nl
authors.forename: A C
authors.initials: AC
authors.lastname: Lim
authors.forename: E
authors.initials: E
authors.lastname: Schuit
authors.forename: D
authors.initials: D
authors.lastname: Papatsonis
authors.forename: J
authors.initials: J
authors.lastname: van Eyck
authors.forename: M M
authors.initials: MM
authors.lastname: Porath
authors.forename: C M
authors.initials: CM
authors.lastname: van Oirschot
authors.forename: P
authors.initials: P
authors.lastname: Hummel
authors.forename: T H M
authors.initials: TH
authors.lastname: Hasaart
authors.forename: G
authors.initials: G
authors.lastname: Kleiverda
authors.forename: I M
authors.initials: IM
authors.lastname: de Graaf
authors.forename: A A
authors.initials: AA
authors.lastname: van Ginkel
authors.forename: B W J
authors.initials: BW
authors.lastname: Mol
authors.forename: H W
authors.initials: HW
authors.lastname: Bruinse
mesh_terms: D000077713:17 alpha-Hydroxyprogesterone Caproate; D000328:Adult; D054791:Cervical Length Measurement / Q000187:drug effects*; D002584:Cervix Uteri / Q000187:drug effects* / Q000473:pathology; D005260:Female; D005865:Gestational Age; D006801:Humans; D006908:Hydroxyprogesterones / Q000008:administration & dosage / Q000494:pharmacology*; D007231:Infant, Newborn; D011247:Pregnancy; D059285:Pregnancy, Twin; D047928:Premature Birth / Q000517:prevention & control*; D011372:Progestins / Q000008:administration & dosage / Q000494:pharmacology*; D002581:Uterine Cervical Incompetence / Q000188:drug therapy* / Q000473:pathology
chemical_list: D006908:Hydroxyprogesterones; D011372:Progestins; D000077713:17 alpha-Hydroxyprogesterone Caproate