Original Research Articles

The association between pre-pregnancy body mass index and gestational weight gain (GWG) among women in rural NSW, Australia

Background: Pre-pregnancy body mass index (BMI) and excessive gestational weight gain (GWG) are associated with adverse outcomes of pregnancy. The Institute of Medicine (IOM) provides recommendations for weight gain during pregnancy based on pre-pregnancy BMI.

Objectives: To evaluate the proportion of pregnant women in a rural medical practice not meeting the IOM guidelines and to assess a link between pre-pregnancy BMI or excessive GWG and delivery method in this population.

Methods: A clinical audit of 168 patients in a rural NSW Medical Centre with a search criterion of ‘pregnancy’ was performed. Relevant patient details were collected and linked to patient files; pre-pregnancy weight, height, weights recorded during pregnancy, and delivery method.

Results: Among the 87% of gestating women who did not meet the current GWG recommendations, 57% gained weight excessively and 30% inadequately. There was a statistically significant association between pre-pregnancy BMI and excessive GWG with overweight women more likely to gain excessively (Fisher’s exact test 29.04, p<0.001). Pre-pregnancy BMI was also associated with delivery method, with normal weight women more likely to have a normal vaginal delivery and obese women more likely to have an instrumental delivery or planned Caesarean-section (Fisher’s exact test 20.89; p<0.001). Gestational weight gain was not associated with delivery method, regardless of pre-pregnancy BMI.

Conclusion: Given that the majority of women in this rural medical practice showed gestational weight gains outside the recommended limits and that pre-pregnancy BMI was associated with delivery method, there is a role for pre-conception and antenatal programs educating women regarding healthy pre-pregnancy weight and GWG.

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