Technical Paper 1:
Obesity in Australia: a need for urgent action
Obesity has become a serious global public health issue and has consequences for nearly all areas of medicine. Within obstetrics, obesity not only has direct implications for the health of a pregnancy but also impacts on the weight of the child in infancy and beyond. As such, maternal weight may influence the prevalence and severity of obesity in future generations. Pregnancy may be a good time to target health behaviour changes by using the extra motivation women tend to have at this time to maximise the health of their child.
A 2009 review of the current evidence for interventions to promote weight control or weight loss in women around the time of pregnancy found few intervention strategies to have been suggested in the published literature, in spite of numerous reports of the prevalence and complications of maternal obesity. The review also concluded that there is a deficiency of appropriately designed interventions for maternal obesity and highlights areas for developing a more effective strategy.
A systematic review and meta-analysis examined the association between increasing maternal BMI and elective/emergency caesarean delivery rates. Caesarean delivery risk was found to increase by 50% in overweight women and to be more than double for obese women compared with women with normal BMI.
A review published in 2009 on obesity, gestational diabetes and pregnancy outcomes noted the rising prevalence of both obesity and gestational diabetes mellitus (GDM) globally. Evidence on the complications of diabetes affecting the mother and foetus is clear: maternal complications include preterm labour, pre-eclampsia, nephropathy, birth trauma, caesarean section and postoperative wound complications. Foetal complications include foetal wastage from early pregnancy loss or congenital anomalies, macrosomia, shoulder dystocia, stillbirth, growth restriction and hypoglycaemia. The presence of obesity among diabetic patients compounds these complications. The review found that short-term complications can be mediated by achieving the desired level of glycaemic control during pregnancy. However, GDM during pregnancy is associated with increased risk of early obesity, type 2 diabetes during adolescence and the development of metabolic syndrome in early childhood. In addition, GDM is a marker for the development of overt type 2 diabetes and metabolic syndrome for the mother in the early future.
Top of Page
WHO published a report in 2007 entitled ‘Evidence of the long-term effects of breastfeeding: systematic reviews and meta-analysis’. The report concluded that ‘the evidence suggests that breastfeeding may have a small protective effect on the prevalence of obesity’, and that the protective effect of breastfeeding was not likely to be due to publication bias. A overview by Cope and Allison published in 2008 which critiqued the section of the WHO report on breastfeeding and obesity concluded that, while breastfeeding may have benefits beyond any putative protection against obesity, and the benefits of breastfeeding most likely outweigh any harms, any statement that a strong, clear or consistent body of evidence shows that breastfeeding causally reduces the risk of overweight or obesity is unwarranted at this time.
A US review used 1990 US Institute of Medicine (IOM) gestational weight gain recommendations to determine healthy weight gain during pregnancy. The review examined the relationship of gestational weight gain to infant size at birth; pregnancy, labour and delivery complications; neonatal, infant and child outcomes; and maternal weight and health outcomes in US and European populations. It was found that pregnancy weight gains within IOM recommendations are associated with better outcomes. The possible exception is very obese women, who may benefit from weight gains less than the 7kg recommended. Review findings indicated that only about 33% to 40% of US women gained weight within IOM recommendations. Excessive gestational weight gain was found to be more prevalent than inadequate gain, and women’s gestational weight gains tended to follow the recommendations of healthcare providers. The review identified opportunities for advice and intervention to minimise weight gain among pregnant women, with current interventions demonstrating efficacy in influencing gestational weight gain in low-income women with normal and overweight BMI in the United States and obese women in Scandinavia.
A review published in 2008 examining the impact of obesity on female fertility and fertility treatment highlighted the extent of the impact obesity and overweight have on reproductive health. The authors found there to be a high prevalence of obese women in the infertile population, with numerous studies demonstrating the link between obesity and infertility. Obesity contributes to anovulation and menstrual irregularities, reduced conception rate and a reduced response to fertility treatment, as well as increasing miscarriage and contributing to maternal and perinatal complication. Reduction in obesity, particularly abdominal obesity, is associated with improvements in reproductive functions; the authors therefore recommended that treatment of obesity itself should be the initial aim in obese infertile women, before embarking on ovulation-induction drugs or assisted reproductive techniques. Despite the existence of weight-reduction strategies such as pharmacological and surgical interventions, the authors concluded that lifestyle modification continues to be of paramount importance.
Top of Page