title: The effects of an increasing gradient of maternal obesity on pregnancy outcomes.
abstract: BACKGROUND
  Maternal obesity is becoming more prevalent in obstetrics and has been linked with pregnancy complications and perinatal outcomes. The gradient of association of increasing maternal obesity and pregnancy outcome is less well studied.
  
  
  OBJECTIVE
  To determine the influence of an increasing gradient of obesity, categorised by the body mass index (BMI), on pregnancy outcomes and to determine the BMI thresholds at which pregnancy complications occur.
  
  
  METHODS
  Secondary analysis of an observational study on pregnancy and obesity. The BMI at the first prenatal visit was grouped into BMI categories (<18.5, 18.5-24.9, 25-29.9, 30-34.9, 35-39.9, 40-44.9, and ≥45) and compared with the normal category (BMI 18.5-25) for pregnancy outcomes and adjusted for known cofounders.
  
  
  RESULTS
  A total of 4,490 women were stratified into the pre-pregnancy BMI categories: <18.5 (n = 276), 18.5-24.9 (n = 1965), 25-29.9 (n = 1072), 30-34.9 (n = 551), 35-39.9 (n = 317), 40-44.9 (n = 167), and ≥45 (n = 142). The maternal demographics were significantly different between BMI groups (P < 0.001). Compared to women with a normal BMI, different BMI thresholds convey an increased risk for specific pregnancy complications: BMI≥25 for gestational diabetes (P < 0.001), induction of labour (P < 0.001), caesarean delivery (P < 0.001) and large for gestational age neonate (P < 0.001); BMI≥30 for pre-eclampsia (P < 0.001), wound infection (P = 0.001), shoulder dystocia (P < 0.001) and meconium (P = 0.006); BMI≥35 for urinary tract infection (P < 0.001) and postpartum haemorrhage (P < 0.001); BMI≥40 for endometritis (P < 0.001).
  
  
  CONCLUSIONS
  Body mass index thresholds exist at which pregnancy complications significantly increase and they vary depending on outcome ranging from BMI ≥25 to a BMI ≥40.
authors: Department of Obstetrics and Gynecology, University of Arkansas for the Medical Sciences, Little Rock, AR, USA. efmagann@uams.edu
authors: Everett F
authors: EF
authors: Magann
authors: Dorota A
authors: DA
authors: Doherty
authors: Adam T
authors: AT
authors: Sandlin
authors: Suneet P
authors: SP
authors: Chauhan
authors: John C
authors: JC
authors: Morrison
mesh_terms: D000328:Adult; D015992:Body Mass Index; D005260:Female; D006801:Humans; D009765:Obesity / Q000150:complications*; D011247:Pregnancy; D011248:Pregnancy Complications; D011256:Pregnancy Outcome; D055815:Young Adult