Abstract:
The global obesity epidemic is escalating with increased deaths from obesity-related chronic health conditions. New Zealand (NZ) has high rates of obesity especially in Māori and Pacific populations, including pregnant women, who also often gain excess weight during their pregnancy. Obesity in pregnancy and excessive gestational-weight-gain (GWG) each increase risks of complications for both mother and baby; as well as risks of childhood obesity and consequential adult obesity which can perpetuate the inter-generational cycle of obesity.
Counties Manukau Health (CMH) in NZ is an area of high deprivation, comprising multi-ethnic populations, with high rates of obesity in pregnancy. “External Review of Maternity Care in the Counties Manukau District 2012” highlighted the association of obesity with increased perinatal mortality particularly in Pacific populations. Recommendations were made for CMH to develop culturally appropriate interventions for women with obesity in pregnancy to improve outcomes. This thesis is a response to those recommendations.
A literature review was performed to identify nutritional interventions in pregnancy that may improve outcomes. Obesity could not be modified during pregnancy, but a meta-analysis of dietary interventions reported reductions in pregnancy weight-gain, gestational-diabetes-mellitus (GDM), hypertensive-disorders-of-pregnancy (HDP), preterm births and shoulder dystocia. In addition, community health workers (CHWs) and text messaging have assisted in delivery of pregnancy interventions. Probiotics have also been reported to reduce GDM. My literature review identified a knowledge gap in the effectiveness of probiotics to treat GDM (common complication of obesity and excessive GWG). A Cochrane systematic review was therefore performed which demonstrated limited evidence to support the use of probiotics for the treatment of GDM.
A survey “Knowledge and beliefs about nutrition and physical activity in pregnancy” was administered in CMH. Of 422 pregnant participants, 83.4% reported they would likely participate in a nutritional intervention during pregnancy; to improve their health and that of their baby.
Survey results contributed to development of a randomised controlled trial (RCT) the Healthy Mums and Babies (HUMBA) Trial. The purposes of the trial were: to determine whether a dietary intervention delivered by CHWs and supported by text messages with probiotics or placebo versus routine dietary advice with probiotics or placebo, reduced maternal excessive GWG and optimised birthweight (primary outcomes). The results of the RCT showed that neither dietary interventions nor probiotics had any effect on the primary outcomes. However, dietary
intervention was associated with moderate reduction in total GWG (adjusted mean difference - 1.76kg, 95% CI -3.55 to 0.03). There were no short-term benefits with probiotics. There was no significant interaction between randomisation factors (dietary intervention versus routine advice with probiotics or placebo) for primary maternal (P = 0.89) and neonatal (P = 0.48) outcomes.
Finally, women who had participated in the HUMBA RCT were surveyed about their experiences of taking part in the trial. Most enjoyed participating and would recommend dietary intervention delivered by CHWs, text messages and probiotics to a friend, if there was evidence that outcomes were improved.
This thesis has added to the current literature on effect of dietary interventions and probiotics in pregnancy, in women with obesity. There is inadequate evidence to recommend use of probiotics as treatment for GDM. This HUMBA RCT in this high-risk population was feasible and dietary intervention delivered by CHWs resulted in lower total GWG. Women enjoyed participating in the HUMBA Trial and lessons learned can form the basis for future trials.