title: Does general exercise training before and during pregnancy influence the pelvic floor "opening" and delivery outcome? A 3D/4D ultrasound study following nulliparous pregnant women from mid-pregnancy to childbirth.
abstract: BACKGROUND
  It has been suggested that women who are regular exercisers have a tighter pelvic floor and thereby have more difficulty during childbirth than non-exercising women. We investigated whether women exercising before and during pregnancy have a narrower levator hiatus (LH) area than their sedentary counterparts. We also studied whether regular exercise at gestational week 37 influences delivery outcome.
  
  
  METHODS
  Cohort study of 274 nulliparous pregnant women assessed at mid-pregnancy and gestational week 37 by three-dimensional/four-dimensional transperineal ultrasonography of the LH area. Exercisers were defined as those exercising ≥30 min three times per week and non-exercisers as not exercising. Exercise data were collected via electronic questionnaire at mean gestational weeks 21 and 37. Labour and delivery outcomes were collected from the women's electronic medical birth records. Differences between exercisers and non-exercisers were analysed using independent sample t test or χ(2) test. p Value was set to ≤0.05.
  
  
  RESULTS
  At gestational week 37, exercisers had a significantly larger LH area than non-exercisers at rest and during PFM contraction (mean difference -1.6 cm(2) (95% CI -3.0 to -0.3), p=0.02 and -1.1 cm(2) (95% CI -2.0 to -0.1), p=0.04, respectively). No significant differences were found between exercisers and non-exercisers at week 37 in any labour or delivery outcomes.
  
  
  CONCLUSIONS
  The results of the present study do not support the hypothesis that women exercising regularly before or during pregnancy have a narrower LH area or more complicated childbirths than non-exercising women.
  
  
  BACKGROUND
  ClinicalTrials.gov: NCT01045135.
authors.affiliation: Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway Department of Obstetrics and Gynecology, Akershus University Hospital, Lørenskog, Norway.
authors.forename: Kari
authors.initials: K
authors.lastname: Bø
authors.affiliation: Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway Department of Obstetrics and Gynecology, Akershus University Hospital, Lørenskog, Norway.
authors.forename: Gunvor
authors.initials: G
authors.lastname: Hilde
authors.affiliation: Department of Obstetrics and Gynecology, Akershus University Hospital, Lørenskog, Norway.
authors.forename: Jette
authors.initials: J
authors.lastname: Staer-Jensen
authors.affiliation: Department of Obstetrics and Gynecology, Akershus University Hospital, Lørenskog, Norway Faculty Division, Akershus University Hospital, University of Oslo, Oslo, Norway.
authors.forename: Franziska
authors.initials: F
authors.lastname: Siafarikas
authors.affiliation: Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway Department of Obstetrics and Gynecology, Akershus University Hospital, Lørenskog, Norway.
authors.forename: Merete Kolberg
authors.initials: MK
authors.lastname: Tennfjord
authors.affiliation: Department of Obstetrics and Gynecology, Akershus University Hospital, Lørenskog, Norway Faculty Division, Akershus University Hospital, University of Oslo, Oslo, Norway.
authors.forename: Marie Ellstrøm
authors.initials: ME
authors.lastname: Engh
mesh_terms: D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D009119:Muscle Contraction / Q000502:physiology; D007744:Obstetric Labor Complications / Q000209:etiology* / Q000503:physiopathology; D017773:Pelvic Floor / Q000502:physiology; D011247:Pregnancy; D011256:Pregnancy Outcome; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal / Q000379:methods*
keywords: Core stability; Exercise; Physical activity promotion in primary care; Ultrasound; Women