Includes bibliographical references.Background. Obesity is increasing globally and is defined as a Body Mass Index (BMI) over 30 kgms/m². It’s prevalence in the Metro West Maternity service is unknown. Objective .To assess the prevalence of obesity and determine its association with adverse perinatal and maternal outcomes among pregnant women in the Metro West Region, Cape Town, South Africa Study Design. This was a retrospective observational study that compared perinatal outcomes in women with normal pregnancy BMI to outcomes in women with high pregnancy BMI. Setting. Mitchells Plain and Guguletu Midwife Obstetric Units, Mowbray Maternity Hospital and Groote Schuur Hospital, Metro West Region, Cape Town, South Africa Population. A total of 970 pregnant women divided into BMI groups that had their first antenatal booking visit between January and April 2011. Methods. A list of folder numbers was compiled from the antenatal booking registry at the two MOUs. From the list, maternal folders were then traced through the CLINICOM tracking system, MOU delivery registers, antenatal clinic transfer registers and labour ward transfer registers to find place of delivery or outcome of pregnancy. Maternal and perinatal characteristics were then extracted from the folders into the data collection sheet and data was analysed by STATA. Descriptive statistics included proportions with percentages and median with interquartile ranges. Inferential statistics included Chisquared tests, Fisher Exact tests, Kruskal Wallis test, univariate and multivariable logistic regressions. Main outcome measures. Perinatal outcomes (stillbirth, macrosomia, shoulder dystocia, 5 minute Apgar Score less than 7, congenital abnormalities) observed in obese and morbidly obese compared to normal BMI pregnant women