The impact of body mass index on maternal and neonatal outcomes: a retrospective study in a UK obstetric population, 2004–2011

OBJECTIVE: To assess the prevalence of overweight and obesity, and the impact of body mass index (BMI) on maternal and neonatal outcomes, in a UK obstetric population. DESIGN: Retrospective study. SETTING: A tertiary referral unit in Northern Ireland. POPULATION: A total of 30 298 singleton pregnancies over an 8-year period, 2004-2011. METHODS: Women were categorised according to World Health Organization classification: underweight (BMI 5 days (OR 2.1, 99% CI 1.5-3.1), and infant requiring admission to a neonatal unit (OR 1.6, 99% CI 1.0-2.6). CONCLUSIONS: By categorising women into overweight and obesity subclassifications (classes I -III), this study clearly demonstrates an increasing risk of adverse outcomes across BMI categories, with women who are overweight also at significant risk.