Although pregnancy may be considered an opportune time for medical practitioners to engage women in discussions about the effects of obesity, it is usually "too little too late" for any meaningful benefit, according to the authors of a Perspective published in Medical Journal of Australia.

More than 50% of women are now overweight or obese at the start of a pregnancy, and this can have adverse consequences that include gestational diabetes, hypertension during pregnancy and pre-eclampsia. However, according to Associate Professor Kirsten Black and Dr Adrienne Gordon from the University of Sydney and Royal Prince Alfred Hospital, pregnancy is not an ideal time for starting to lose weight.

"Trials of antenatal interventions undertaken with the aim of limiting gestational weight gain by obese women have had only limited success in improving important perinatal outcomes, such as rates of caesarean delivery, large for gestational age (LGA) babies, neonatal birthweight, and macrosomia," the authors wrote.

Instead, evidence is growing that obesity should be tackled before pregnancy if interventions are to have any effect. But capturing those who need pre-conception care is complicated by the fact that one-third of pregnancies that proceed to antenatal care are unplanned.

"Another significant problem is the lack of evidence on which to base recommendations about weight loss and lifestyle interventions before pregnancy for improving maternal and neonatal outcomes; randomised trials concerned with pre-pregnancy weight have thus far focused on obesity and reduced fertility," the authors wrote. The authors recommended that a pragmatic approach might be to educate women about the effects of obesity during their pregnancy and the post-natal period, and to advise them of postnatal programs for reducing the risk of post partum weight retention and therefore of obesity during later pregnancies.

"This approach will require hospitals and health services to take a more long term perspective of pregnancy and the post partum period, as well as government investment in these public health strategies," the authors advised.

Article: Obesity before pregnancy: new evidence and future strategies, Kirsten I Black and Adrienne Gordon, Medical Journal of Australia, doi: 10.5694/mja16.00469, published 15 August 2016.