Pre-pregnancy and early pregnancy dietary behavior in relation to maternal and newborn health in the Norwegian Fit for Delivery study – a post hoc observational analysis

BACKGROUND: Randomized controlled trials targeting maternal dietary and physical activity behaviors during pregnancy have generally failed to accomplish reductions in the prevalence of adverse maternal and neonatal outcomes. Interventions carried out during pregnancy could thus be missing the mark in maximizing intervention health benefit. OBJECTIVE: To investigate whether pre-pregnancy and early pregnancy dietary behavior as reported at inclusion into the Norwegian Fit for Delivery (NFFD) trial was associated with maternal and neonatal outcomes irrespective of subsequent randomization assignment. DESIGN: The study is a post-hoc observational analysis of data from a randomized controlled lifestyle intervention. We constructed two diet scores from participant responses to a 43-item questionnaire that addressed dietary behavior in retrospect (pre-pregnancy diet score) and dietary behavior at inclusion (early pregnancy diet score), respectively. The diet scores ranged from 0 to 10, with higher score reflecting healthier dietary behavior. Associations between diet scores and maternal and neonatal health outcomes were estimated in multivariate logistic regression models. RESULTS: A total of 591 women were eligible for analysis. A one-point increase in pre-pregnancy diet score was associated with lower odds of excessive gestational weight gain (GWG) (odds ratio [OR](adj): 0.92; 95% confidence interval [CI]: 0.84–1.00, p = 0.050), preterm delivery (OR(adj): 0.81; 95% CI: 0.68–0.97, p = 0.019), and birthweight ≥ 4,000 g (OR(adj): 0.88; 95% CI: 0.78–0.99, p = 0.038). A one-point increase in early pregnancy diet score was associated with lower odds of excessive GWG (OR(adj): 0.88; 95% CI: 0.79–0.97, p = 0.009), preterm delivery (OR(adj): 0.82; 95% CI: 0.67–0.99, p = 0.038), and preeclampsia (OR(adj): 0.78; 95% CI: 0.62–0.99, p = 0.038). DISCUSSION: Higher diet score either pre-pregnancy or in early pregnancy was protectively associated with excessive GWG and preterm delivery, whereas the protective association with high birthweight was confined to pre-pregnancy diet and with preeclampsia to early pregnancy diet. CONCLUSIONS: Both pre-pregnancy and early pregnancy dietary behavior was associated with important maternal and neonatal health outcomes in the NFFD dataset.