Aims: We will examine the relationships between antenatal mental health, BMI, diet quality and GWG. We aim to investigate whether pre-pregnancy BMI and mental health problems during pregnancy are related to poor quality diet (both dietary patterns and nutritional intakes) and excessive GWG.

Hypotheses: We hypothesise that, after adjusting for potential confounders: 1) A less healthy dietary pattern (higher proportions of energy dense foods and lower proportions of vitamin rich foods) and more excessive GWG will be reported by women with antenatal depression and anxiety compared with women without mental health problems. 2) A less healthy dietary pattern (higher proportions of energy dense foods and lower proportions of vitamin rich foods) and more excessive GWG will be found in overweight/obese women compared with normal weight women. 3) A less healthy dietary pattern (higher proportions of energy dense foods and lower proportions of vitamin rich foods) and more excessive GWG will be reported by high BMI women with depression/anxiety compared with high BMI women without these mental health problems. The interaction between BMI and mental health will be investigated.

Analysis:The effect of mental health on diet quality and GWG will be examined in the sample as a whole and in subgroups of women with normal (18.5-25kg/m2) and high (greater than 25kg/m2) pre-pregnancy BMI. The interaction between mental health and BMI will be investigated. The effects of socioeconomic status, maternal age, smoking and other confounders will be examined.