Prospective relationships between health cognitions and excess gestational weight gain in a cohort of healthy and overweight pregnant women

Background: Excess gestational weight gain (GWG) contributes to long-term obesity in mothers and children. To guide the tailoring of interventions to prevent excess GWG, a better understanding is needed of the lifestyle-related health cognitions that influence women’s attempts to manage GWG. Objective: To examine the relationship between health cognitions and excess GWG for women who enter pregnancy at a healthy weight (body mass index < 25) or overweight (body mass index ≥25). It was hypothesized that health cognitions with a positive (negative) influence on health behavior would be associated with lower (higher) likelihood of excess GWG and that specific associations would differ between weight status groups. Design: This prospective, observational study commenced when participants were < 20 weeks’ gestation, continuing until the end of their pregnancy. A self-administered quantitative survey at recruitment assessed prepregnancy weight and lifestyle-related health cognitions. Height was measured at 16 weeks and weight at 36 weeks using standard procedures. Participants and setting: A consecutive sample of pregnant women (n=715) were recruited from an Australian metropolitan hospital between August 2010 and January 2011. All women < 20 weeks’ gestation were eligible unless they had preexisting type 1 or 2 diabetes or insufficient English language skills to complete questionnaires. Main outcome measures: Excess GWG defined according to Institute of Medicine 2009 recommendations and predisposing, reinforcing, and enabling cognitions for lifestyle health behaviors. Statistical analyses performed: Logistic regression analyses examined associations between health cognitions and excess GWG stratified for prepregnancy weight status. Results: For healthy-weight women, higher weight locus of control scores were protective against excess GWG (odds ratio 0.6, 95% CI 0.4 to 0.8), whereas higher perceived risk scores (personal risk and risk arising from prepregnancy weight) (odds ratio 1.3, 95% CI 1.1 to 1.7) were associated with excess GWG. For overweight women higher negative outcome expectation scores were associated with an increased risk of excess GWG (odds ratio 1.4, 95% CI 1.1 to 2.0). Conclusions: Lifestyle-related health cognitions are associated with excess GWG and differed by prepregnancy weight status, suggesting the need to tailor behavior change interventions accordingly.