Dear Editor,

We read with interest the paper by Vasudevan et al. on foetal and perinatal consequences of maternal obesity.(1) The authors highlight the increased risk of perinatal mortality, neural tube and structural cardiac defects in the offspring. They also report an increased risk of birth injuries, perinatal asphyxia, respiratory distress and metabolic instability that are related to the associated foetal macrosomia. In a recent study of 6125 pregnant women (25% of whom were overweight, 12.1% moderately and 7% severely obese), to differentiate between the direct effects of maternal obesity on neonatal outcomes and those caused by confounding factors, such as foetal macrosomia, we used a logistic multivariate analysis.(2) Although the crude unadjusted prevalence of several adverse neonatal outcomes was higher in their offspring, the only two outcomes significantly directly associated with maternal obesity were neonatal macrosomia (adjusted odds ratios aOR 1.4, p < 0.001) and meconium aspiration syndrome (aOR 1.6, p = 0.05). All other neonatal outcomes, such as birth injuries, metabolic disturbances were confounded by the associated foetal macrosomia. In addition we found no significant association with congenital anomalies. This validates the results of a meta-analysis which also showed no significant relationship between maternal obesity and the incidence of neonatal asphyxia, hypoglycaemia or the need for mechanical ventilation.(3) Furthermore, such an association, if it exists, may not necessarily be causal. Therefore, while we agree that prevention of maternal obesity would very likely decrease adverse health risks on the mother, we believe that any resulting decrease in foetal and neonatal complications would be mainly due to decreasing the prevalence of foetal macrosomia, although a causal relationship still needs to be established. There is currently no evidence to support the idea that prevention of maternal obesity has the potential to decrease neonatal complications not directly related to foetal macrosomia. Further research is needed to clarify these issues before any recommendations can be made.

References

1. Vasudevan C, Renfrew M, McGuire W. Fetal and perinatal consequences of maternal obesity. Arch Dis Child Fetal Neonatal Ed 2011;96:F378-82

2. Narchi H, Skinner A. Overweight and obesity in pregnancy do not adversely affect neonatal outcomes: new evidence. J Obstet Gynaecol 2010;30:679-86

3. Heslehurst N, Simpson H, Ells LJ, et al. The impact of maternal BMI status on pregnancy outcomes with immediate short-term obstetric resource implications: a meta-analysis. ObesRev 2008;9:635-83

Conflict of Interest:

None declared