The effect of a 12-week dietary intervention on food intake and diet quality in obese, pregnant women in South Auckland

Abstract

Background and Aim: Excessive weight gain during pregnancy can be detrimental to the health of both a mother and her child. As such, it is critical that appropriate nutrition support is accessible during the gestational period in order to guide appropriate weight gain and reduce the risk of gestational complications. In New Zealand, nutrition advice during pregnancy is centered around the distribution of pamphlets produced by the New Zealand Ministry of Health and is not routinely tailored to each individual. While comprehensive, it is questionable whether the current model is enough to instigate behavioural change or provide enough support for women through a period of such nutritional vulnerability. With increasingly high rates of obesity among childbearing women in South Auckland, the aim of this thesis was to assess the effect of a culturally appropriate nutritional intervention on food intake and diet quality in a cohort of obese, pregnant women in the ethnically diverse Counties Manukau region. Methods: The Healthy Mum's and Babies (HUMBA) Trial was a single centre, two by two randomised controlled demonstration trial which commenced in March 2015. Participants were randomised to receive either routine nutrition support or a 12-week multifaceted nutrition intervention over the course of gestation and/or supplementation with probiotic capsules (Lactobacillus rhamnosus GG and Bifidobacterium lactis BB12). For the purposes of this thesis, only the dietary intervention arm of this trial was investigated. All women were required to complete a semi-quantitative food frequency questionnaire (FFQ) at both recruitment (between 120 and 170 weeks' gestation) and trial conclusion (between 28-30 weeks gestation). FFQ data was extracted and used to assess the impact of intensive nutrition support on food intake and diet quality. This included an analysis of changes in servings of primary food groups, discretionary food groups and beverages alongside pregnancy-related nutrients such as total energy, protein, carbohydrate, fat, iron, iodine and folate. Diet quality was also assessed via comparisons of food and nutrient intakes with national recommendations. Results: 230 women were enrolled and randomised to receive either routine dietary advice (n = 114) or the dietary intervention (n = 116). Of these, 41 did not complete the FFQ at both time points and were excluded from dietary analyses, leaving a total sample of 189 women; 96 in the routine group and 93 in the intervention group. Mixed-effects regression analyses identified a significant difference between the routine and intervention groups at 28 weeks for processed meat, such that women in the intervention group ate significantly less processed meat at 28 weeks compared than those receiving routine dietary advice (p = 0.046). While not significant, results also trended in a positive direction for a number of other food and nutrient categories, notably an increase in mean weekly servings of water, a decrease in mean weekly servings of sweet drinks, a concurrent rise in mean servings of diet soft drinks, an increase in mean servings of healthier breads and cereals and a moderate increase in folate intakes between baseline and 28 weeks.