There is a deficit of prospective, up-to-date research investigating gastrointestinal function during and after pregnancy, particularly in relation to non-starch polysaccharide (NSP) and water intakes, and physical activity levels. The aims of the work reported in this thesis were to investigate habitual dietary intake, patterns of physical activity and bowel function and their inter-relationships throughout and after pregnancy. Ninety-four subjects were recruited from three London Teaching Hospitals and a magazine advertisement. Seventy-two, 59, 62 and 55 subjects participated in the first, second, third and postpartum study stages respectively and 42 participants completed every study stage. Volunteers completed a screening questionnaire, 4-7 -day weighed inventory food diary, physical activity questionnaire and bowel function diary prospectively at mean weeks 13, 25, 35 of gestation and 6 weeks after birth, in addition to a postnatal questionnaire. No statistically significant differences were observed when data was compared between the 42 volunteers that completed the study longitudinally and higher subject numbers. Findings indicated that only 47% of women met the 18 g/d population average NSP recommendation during pregnancy and 41 % after birth. Women participated in statistically significantly higher levels of vigorous activities in the first trimester when compared with these activities in the puerperium (P