title: Risk factors for macrosomia and its clinical consequences: a study of 350,311 pregnancies.
abstract: OBJECTIVE
  To identify demographic risk factors for either birthweight >4kg or over the 90th centile and to quantify the obstetric risks.
  
  
  METHODS
  Data from 350,311 completed singleton pregnancies in the North West Thames Region between 1988 and 1997 were analysed using logistic regression. Predisposing factors and pregnancy outcome were compared by birthweight 2.5-4kg (n=259,902) and >4kg (n=36,462) and 10th-90th centile (n=279,780) and >90th centile (n=34,937).
  
  
  RESULTS
  Macrosomia defined as birthweight >90th centile was more likely in women whose BMI >30 (kg/m(2)) (odds ratio (OR) 2.08; confidence intervals (CI) 1.99, 2.17), parity >4 (OR 2.20; CI 2.02, 2.40), age >40 (OR 1.22; CI 1.11, 1.35) and in women with pre-existing diabetes (OR 6.97; CI 5.36, 8.16) or who developed gestational diabetes (OR 2.77; CI 2.51, 3.07). Macrosomia defined by birthweight >4kg was better than birthweight >90th centile at predicting morbidity and was associated with a prolonged first and second stage of labour (OR 1.57; CI 1.51, 1.63) and (OR 2.03; CI 1.88, 2.19), respectively, an increased risk of instrumental vaginal delivery (OR 1.76; CI 1.68, 1.85), third degree perineal trauma (OR 2.73; CI 2.30, 3.23), emergency caesarean section (OR 1.84; CI 1.75, 1.93), postpartum haemorrhage (OR 2.01; CI 1.93, 2.10), Apgar score <4 (OR 1.35; CI 1.03, 1.76), and admission to the special care baby unit (OR 1.51; CI 21.38, 1.68).
  
  
  CONCLUSIONS
  Macrosomia is more common in mothers who are obese, older or diabetic and is associated with significant obstetric morbidity.
authors.affiliation: Section of Endocrinology and Metabolic Medicine, The Mint Wing, Imperial College of Science Technology and Medicine, St. Mary's Campus, London W2 1PG, UK. matthew.jolly@rws-tr.nhs.uk
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Jolly
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Sebire
authors.forename: John P
authors.initials: JP
authors.lastname: Harris
authors.forename: Lesley
authors.initials: L
authors.lastname: Regan
authors.forename: Stephen
authors.initials: S
authors.lastname: Robinson
mesh_terms: D000293:Adolescent; D000328:Adult; D036861:Delivery, Obstetric / Q000706:statistics & numerical data; D016640:Diabetes, Gestational / Q000150:complications / Q000453:epidemiology; D004739:England / Q000453:epidemiology; D005260:Female; D005320:Fetal Macrosomia / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D008423:Maternal Age; D006473:Postpartum Hemorrhage / Q000453:epidemiology / Q000209:etiology; D011247:Pregnancy; D011256:Pregnancy Outcome; D011254:Pregnancy in Diabetics / Q000150:complications / Q000453:epidemiology; D012307:Risk Factors