Aims: The primary aim of this study was to describe pregnant women's perception of increased risk due to excess weight in pregnancy. The secondary aims were: To describe pregnant women's knowledge of weight gain recommendations. To assess the weight of pregnant women and to examine women's knowledge of their own weight. Methods: A cross-sectional, self-administered survey of 411 pregnant women attending a nuchal translucency scan at 11 to 13+6 weeks gestation in four community radiology units in Christchurch during a four month period in 2012. The main outcome measure was knowledge regarding the risks of excess weight in pregnancy. Knowledge related to the risks of smoking in pregnancy was also considered. Following a literature search, nine events/complications of pregnancy were included in the questionnaire: stillbirth, small for gestational age, macrosomia, complicated vaginal delivery, structural anomaly, caesarean section, high blood pressure, gestational diabetes mellitus and shoulder dystocia. Statements related to knowledge of risks were posed as: smoking/excess weight in pregnancy increases your risk of: for example, gestational diabetes. Participants were asked to rate their level of agreement of increased risk on a seven-point likert scale from 'strongly agree' to 'strongly disagree' The option 'I don't know' was also given. For analysis, a panel of three specialist obstetricians identified the answers they considered 'ideal' for each question, i.e. the appropriate level of agreement or disagreement. Sociodemographic data were collected. Participants were asked to identify their BMI status (underweight, normal weight, overweight or obese) and target gestational weight gain. Options for gestational weight gain included the 2009 Institute of Medicine weight gain in pregnancy guidelines and the answers 'I should not gain any weight' and 'it does not matter how much weight I gain'. Participants had their height and weight measured using calibrated equipment and their BMI calculated. Conclusion:This study indicates a number of areas where knowledge is lacking, including the risks of excess weight in pregnancy and appropriate weight gain for pregnancy. This may be exacerbated by the fact a large number of women are not being weighed in early pregnancy and that many women are not aware of their true body size, with the vast majority of overweight and obese women underestimating their body size.