title: Observational study of associations between gestational weight gain and perinatal outcomes in dichorionic twin pregnancies.
abstract: OBJECTIVE
  To evaluate relationships between gestational weight gain (GWG) and adverse events during pregnancy among patients of normal weight with twin pregnancies.
  
  
  METHODS
  The present observational study included patients with dichorionic twin pregnancies with a pre-gravid body mass index of 18.5-24.99 kg/m2who underwent delivery at no earlier than 22 weeks of pregnancy between January 1, 2007, and June 30, 2016, at the Medical University of Warsaw, Warsaw, Poland. The GWG ratio was categorized as low (<0.45 kg/wk), adequate (0.45-0.66 kg/wk), or high (>0.66 kg/wk), and pregnancy outcomes were compared between the GWG ratio groups. Associations between GWG ratio and pregnancy outcomes were estimated using generalized additive models.
  
  
  RESULTS
  There were 201 patients included in the study. No differences in rates of preterm delivery, very preterm delivery (VPTD), small for gestational age fetus, pre-eclampsia, gestational diabetes, preterm premature rupture of membranes, or intrauterine fetal demise were observed between the patient groups. Linear relationships with GWG ratio were recorded for VPTD (P=0.019) and spontaneous VPTD (P=0.003); non-linear relationships with GWG ratio were recorded for pre-eclampsia (P=0.023) and perinatal mortality (P=0.015). A GWG ratio of 0.55-0.56 kg/wk appeared optimal in terms of twin pregnancy outcomes.
  
  
  CONCLUSIONS
  The incidence of VPTD, pre-eclampsia, and perinatal mortality during dichorionic twin pregnancy were associated with GWG ratio.
authors.affiliation: 1st Department of Obstetrics and Gynecology, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kosinska-Kaczynska
authors.affiliation: 1st Department of Obstetrics and Gynecology, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Iwona
authors.initials: I
authors.lastname: Szymusik
authors.affiliation: Department of Medical Informatics and Telemedicine, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Bartosz
authors.initials: B
authors.lastname: Kaczynski
authors.affiliation: 1st Department of Obstetrics and Gynecology, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Miroslaw
authors.initials: M
authors.lastname: Wielgos
mesh_terms: D000328:Adult; D005260:Female; D005865:Gestational Age; D006801:Humans; D062071:Infant, Extremely Premature; D007231:Infant, Newborn; D054238:Perinatal Mortality; D011225:Pre-Eclampsia / Q000453:epidemiology*; D011247:Pregnancy; D011256:Pregnancy Outcome; D059285:Pregnancy, Twin / Q000706:statistics & numerical data*; D047928:Premature Birth / Q000453:epidemiology*; D011446:Prospective Studies; D014429:Twins, Dizygotic; D015430:Weight Gain
keywords: Body mass index; Gestational weight gain; Intrauterine fetal demise; Pre-eclampsia; Preterm delivery; Twin gestation