Abstract:
Background: The prevalence of gestational diabetes mellitus (GDM), a condition of
glucose intolerance in pregnancy with significant health implications for mother and infant, is
rising. Diet is central to managing GDM but little is known about the diets of women with GDM and
how GDM is managed through diet in New Zealand. Objectives: To describe the diets and investigate
the dietary management of women with GDM in New Zealand through four perspectives: an
estimation of the prevalence of GDM in New Zealand; adherence to dietary guidelines and
description of dietary patterns of women with and without GDM and determination of whether these
are associated with the development of GDM; evaluation of dietetic services provided for women with
GDM, and exploration of women’s perceptions of dietary advice and experiences in managing GDM
through diet. Methods: The prevalence of GDM in pregnant women participating in the Growing Up in
New Zealand (GUiNZ) longitudinal birth cohort was determined using clinical coding data, laboratory
results and self-reported data. Adherence to dietary guidelines and dietary patterns were compared
between women with and without GDM participating in GUiNZ from food frequency questionnaires.
Dietetic practice in the management of GDM in New Zealand and the level of dietetic services
provided were evaluated through a cross-sectional survey. Semi- structured interviews with
women with GDM were analysed thematically to explore women’s perceptions of dietary recommendations
and the influence of these on dietary decisions during pregnancy and beyond.
Findings: Prevalence of GDM among 6,822 women participating in GUiNZ combining all data sources was
6.2% but varied significantly according to data source (3.8% using self-reported data to 6.9% from
laboratory data). Dietary data were available from 5,384 women in GUiNZ. Adherence to food group
recommendations was poor in both women with and without GDM and was not associated with odds of
developing GDM. However, mean dietary pattern scores for “Junk” and “Traditional/White
bread” dietary patterns were significantly lower in women with GDM compared to women without
GDM and were negatively associated with having GDM. Thirty- three dietitians participated in the
survey of dietetic practice and reported significant variation in the services provided and
management recommendations. Over a quarter of dietitians felt the services provided
were inadequate but few evaluated their services. Three interconnected themes described
the experience and perceptions of eighteen women with GDM in managing their diet through GDM:
managing GDM is a balancing act; using the numbers as evidence, and the GDM timeframe. Women
perceived the purpose of dietary advice to be control of blood glucose results. Women’s
relationships with healthcare providers had a significant influence on their perception of
advice and dietary intentions.
Conclusions: A consistent national approach to diagnosis and reporting GDM prevalence is needed to
monitor changing prevalence and to facilitate resource allocation and service planning. New
Zealand-specific evidence- based guidelines for the dietary management of GDM are needed to improve
consistency in services and provide a benchmark for the ongoing evaluation of dietetic
management of GDM. Healthcare professionals have a significant influence on women’s dietary
behaviours. A woman-centred approach is necessary to achieve optimal
outcomes for mother and infant.