Abstract
Pregnancy and the transition to motherhood are life-changing events, coupled with a multitude of physiological, psychosocial, and behavioural changes. While being an extremely rewarding experience for many, pregnancy can be associated with long term adverse health outcomes. In particular, excessive gestational weight gain and postpartum weight retention can put mothers at increased risk for a range of non-communicable diseases later in their lives. With the increasing knowledge of the sensory role in food-related behaviour, it is important to study parallel changes in sensory perception and dietary behaviour in mothers and their links to weight issues. To date research regarding mothers’ eating behaviour remains scarce and controversial, with particularly limited research regarding sensory perception. Furthermore, emerging research has suggested links between eating behaviour and sensory perception in other populations, but this has not yet been addressed in mothers. Therefore, this doctoral thesis aimed to systematically evaluate eating behaviour and sensory perception among mothers, and to identify potential sensory-diet links.
The first part of this thesis assessed food-related behaviour and macronutrient preference across mothers and non-mothers, using both habitual and ad-libitum intake measures (Chapter 3, N=223). Mothers’ and non-mothers’ olfactory and gustatory sensitivities (measured by d prime) were then assessed (Chapter 4, N=94) and sensory links to eating behaviour examined (Chapter 5). Additional exploratory research was conducted to determine the influence of culture and the replicability of eating behaviour results from Chapter 3 (Chapter 6, N=570).
Results from Chapter 3 revealed no differences in habitual energy intake between mothers and non-mothers, although the former consumed less energy from savoury carbohydrates in the ad-libitum task and showed a greater preference for high fat foods. Chapter 4 revealed no differences between mothers’ and non-mothers’ sensory perception. Interestingly, vanillin odour sensitivity showed a negative association with years since pregnancy, suggesting sensory perception to return to normal levels after pregnancy. Furthermore, BMI was found to affect both eating behaviour and sensory perception, with mothers showing a higher BMI.
The underlying relationship between eating behaviour and sensory perception was investigated in Chapter 5, with findings indicating different relationships between mothers and non-mothers. Specifically, results revealed mothers’ ad-libitum intake of carbohydrates to be positively associated with and predicted by vanillin odour sensitivity, with the opposite observed in non-mothers. Additionally, mothers’ habitual protein intake was negatively associated with and predicted by savoury odour sensitivity. High fat preference was also associated with savoury odour sensitivity in mothers. These findings suggest differing sensory-eating behaviour relationships may drive differences in eating behaviour between mothers and non-mothers.
The final study tested the effects of culture on mothers’ eating behaviour and whether New Zealand findings could be replicated in another Western country (Denmark). Macronutrient, energy and dietary taste quality intake were assessed through a food frequency questionnaire across New Zealand and Danish mothers and non-mothers. The results indicated no cross-cultural differences with regard to macronutrient and energy intake between countries but marked differences in dietary taste quality intakes. Danish women consumed more food from the ‘Fatty’ taste quality, while New Zealand women showed higher ‘Sweet+Fatty’ food consumption. Furthermore, large differences in dietary intake were observed between New Zealand mothers and non-mothers, with mothers consuming more ‘Sweet+Fatty’, ‘Fatty’, and ‘Umami+Salty+Fatty’ foods and less ‘Neutral’ foods than their non-mother counterparts. Such differences between mothers and non-mothers were not observed in Danish women, suggesting high obesity rates in New Zealand mothers to be related to a change in eating behaviour from pre-pregnancy.
Overall, this thesis is the first to systematically assess eating behaviour and sensory perception, unravelling their connection in mothers. With data from a wide range of measures, stretching from nutrition to sensory science, food choice, and cultural anthropology, this thesis provides novel insights into mothers’ food-related behaviours. These important findings offer a better understanding of changes in eating behaviour and sensory perception among mothers. Furthermore, the findings of this thesis offer fundamental knowledge on driving factors behind mothers’ postpartum weight retention, which can inform and improve future maternal healthcare.