The heavy burden of obesity in pregnancy

The frequency of adverse perinatal outcomes could be reduced by shifting the distribution of overweight and obesity among first-time mothers by a single BMI class

The increasing weight of first-time Australian mothers has wide-reaching impacts on maternal and neonatal health, a large analysis reveals.

Obesity and overweight contributed to the growing proportion of almost all adverse outcomes for women and their children, especially in the case of pre-eclampsia, fetal macrosomia and gestational diabetes, according to the study of 43,000 first-time pregnancies over two decades.

The authors emphasised the need for preventive strategies to address excess weight prior to pregnancy, saying there was increasingly recognition that “by the antenatal period it may be too late to reduce the risks of maternal obesity”.

Unfortunately, the weight of first-time mothers appears to be increasing, with their data showing that from 1990-1994 to 2010-2014 the prevalence of overweight first time pregnant women in the urban Sydney hospital increased from 12.7% to 16.4%. In the same time periods, obesity increased from 4.8% to 7.3%.

The analysis indicated that this increase accounted for 24% of pre-eclampsia, 23% of fetal macrosomia and 17% of gestational diabetes.

In contrast, if women shifted down one BMI class before pregnancy, “substantial” adverse outcomes could be avoided, they wrote.

“Were overweight and obese women to have moved down one BMI category during 2010–2014, 19% of preeclampsia, 15.9% of macrosomia, 14.2% of gestational diabetes, 8.5% of caesarean deliveries, 7.1% of low for gestational age birthweight, 6.8% of post partum haemorrhage, 6.5% of admissions to special care nursery, 5.8% of prematurity, and 3.8% of fetal abnormality could have been averted,” the authors wrote.

“We found that a substantial proportion of the burden of adverse perinatal outcomes for Australian women is linked to maternal overweight and obesity, and that this proportion has steadily increased over the past 25 years,” the authors wrote.

Obesity prevention approaches prior to pregnancy were likely to be the most help, they said.

“Importantly for practice and policy, our results indicate that the frequency of adverse perinatal outcomes could be reduced by shifting the distribution of overweight and obesity among first-time mothers by a single BMI class.”

 MJA 2018; online 12 February