title: Maternal position and ultrasonic cervical assessment in multiple pregnancy. Preliminary observations.
abstract: OBJECTIVE
  To evaluate the influence of position on the functional anatomy of the cervix.
  
  
  METHODS
  Cervical length and width of the internal os were measured by transvaginal ultrasound in the recumbent and standing position from 15 gestational weeks to term in 15 twin and 3 triplet pregnancies. Measurements on asymptomatic primigravidae with twins who delivered vaginally after 36 weeks were made to calculate trends in normal twin pregnancies. These data were compared with that obtained in patients who had threatened preterm labor.
  
  
  RESULTS
  As the total observation period progressed, the mean cervical length decreased from 50 to 27 mm in the recumbent position and from 48 to 21 mm in the standing position (P < .001). The differences between the values obtained in the recumbent and standing position increased from 5% to 31% as pregnancy progressed (P < .001). Funnelling was observed from 20 weeks onwards in the erect position but only after 35 weeks in the recumbent position.
  
  
  CONCLUSIONS
  Our preliminary observations support a policy aimed at prevention of prematurity by reducing physical activity and standing work in patients who have multiple gestations. The full impact of these observations on the early detection of special risk groups and the prescription of preventive interventions have yet to be evaluated.
authors.affiliation: Department of Perinatology, Sophia Ziekenhuis, Zwolle, The Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: Arabin
authors.forename: R
authors.initials: R
authors.lastname: Aardenburg
authors.forename: J
authors.initials: J
authors.lastname: van Eyck
mesh_terms: D002584:Cervix Uteri / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D005260:Female; D005865:Gestational Age; D006801:Humans; D007752:Obstetric Labor, Premature / Q000175:diagnosis / Q000517:prevention & control*; D011187:Posture; D011247:Pregnancy; D011272:Pregnancy, Multiple; D011379:Prognosis; D016216:Ultrasonography, Prenatal; D014621:Vagina / Q000000981:diagnostic imaging