title: The effect of prenatally administered vaginal progesterone on uterine artery Doppler in asymptomatic twin pregnancies.
abstract: OBJECTIVE
  This study investigated the influence of vaginal progesterone on uterine circulation in asymptomatic twin gestations.
  
  
  METHODS
  This study was a secondary analysis of a randomized, double-blind, placebo-controlled trial of twin pregnancies exposed to vaginal progesterone or placebo. We included all trial participants who had undergone uterine artery pulsatility index evaluation at the time of randomization. During each ultrasound examination, the uterine artery pulsatility index was evaluated transabdominally. The mean uterine artery pulsatility index between the progesterone and placebo groups were compared for each gestational age, starting between 18 to 34 weeks and 6days and were analyzed at three (Time 1), six (Time 2) and nine (Time 3) weeks after randomization.
  
  
  RESULTS
  The final analysis included 128 women in the progesterone group and 122 women in the placebo group. The baseline characteristics were similar in both groups. No difference in the mean uterine artery pulsatility index was observed between the progesterone and placebo groups at each week of gestation or throughout gestation.
  
  
  CONCLUSIONS
  In twin pregnancies, the use of vaginal progesterone in the second half of pregnancy does not influence uterine circulation.
authors.affiliation: Department of Obstetrics and Gynaecology, São Paulo University Medical School, Brazil.
authors.forename: Isabela K R
authors.initials: IK
authors.lastname: Agra
authors.affiliation: Department of Obstetrics and Gynaecology, São Paulo University Medical School, Brazil. Electronic address: mlbrizot@uol.com.br.
authors.forename: Maria L
authors.initials: ML
authors.lastname: Brizot
authors.affiliation: Department of Obstetrics and Gynaecology, São Paulo University Medical School, Brazil.
authors.forename: Mariana Y
authors.initials: MY
authors.lastname: Miyadahira
authors.affiliation: Department of Obstetrics and Gynaecology, São Paulo University Medical School, Brazil.
authors.forename: Mário H B
authors.initials: MH
authors.lastname: Carvalho
authors.affiliation: Department of Obstetrics and Gynaecology, São Paulo University Medical School, Brazil.
authors.forename: Rossana P V
authors.initials: RP
authors.lastname: Francisco
authors.affiliation: Department of Obstetrics and Gynaecology, São Paulo University Medical School, Brazil.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Zugaib
mesh_terms: D000282:Administration, Intravaginal; D000328:Adult; D004311:Double-Blind Method; D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011256:Pregnancy Outcome; D059285:Pregnancy, Twin; D011374:Progesterone / Q000008:administration & dosage*; D018608:Ultrasonography, Doppler; D016216:Ultrasonography, Prenatal; D055988:Uterine Artery / Q000000981:diagnostic imaging / Q000187:drug effects*; D055815:Young Adult
chemical_list: D011374:Progesterone
keywords: Doppler velocimetry; Progesterone; Twin pregnancy; Uterine circulation