The perinatal period is a critical time for the development of obesity in mothers and children. Prevention of excess gestational weight gain is a key intervention strategy, however interventions to date have produced mixed results. Identification of the health cognitions associated with excess GWG and its two underpinning behaviours of dietary intake and physical activity may provide insights into lack of consistent positive effects of interventions. The aim of this study was to examine associations between lifestyle specific psychosocial factors and gestational weight gain in pregnant women from the New Beginnings Healthy Mothers and Babies Study. Pregnant women (n=664) aged 29+5 (mean+SD) years completed a questionnaire at 16 weeks gestation assessing pre-pregnancy weight, lifestyle related health cognitions common to dominant health behavior theories including risk perception, self-efficacy, outcome expectations, social support and barriers, and demographic data. Height was measured at recruitment and gestational weight gain assessed at 36 weeks gestation. Logistic regression was used to examine associations between health cognitions and excess GWG, controlling for relevant covariates. One third (34%) of participants had a BMI > 25 kg/m2 prior to pregnancy and 38% gained excess weight. A stronger belief in the ability to control body weight (weight locus of control) was protective against excess GWG (β=-0.344, p=0.024) whereas higher negative outcome expectations were associated with an increased likelihood of excess GWG (β=0.191, p=0.015). Previous experiences associated with success or failure in weight control are likely to play a key role in a healthy gestational weight gain. Consideration of these experiences may be key to successful behaviour change interventions targeting healthy gestational weight gain.