Prepregnancy dietary patterns and risk of preterm birth and low birth weight: findings from the Australian Longitudinal Study on Women's Health

Background: Findings from previous studies on associations between prepregnancy dietary patterns and preterm birth and low birth weight (LBW) are limited and inconsistent. Objectives: To examine the association between prepregnancy dietary patterns and the risk of preterm birth and LBW. Methods: This study included 3422 and 3508 singleton live births from the Australian Longitudinal Study on Women's Health (ALSWH) for the analyses of preterm birth and LBW, respectively. We included women who were nulliparous and nonpregnant at baseline surveys. We used factor analyses and the Healthy Eating Index-2015 (HEI-2015) score to derive maternal dietary patterns. Four dietary patterns were identified with factor analyses: meats and high-fats; prudent diets; sugar, refined grains, and processed foods; and traditional vegetables. Preterm birth and LBW were assessed using maternal reports from ALSWH data between 2003 and 2015. Multivariable logistic regression analyses were used. Results: Greater adherence to the traditional vegetables pattern before pregnancy was associated with a lower risk of preterm birth and spontaneous preterm birth after adjustments for lifestyle factors and pregnancy complications, highest compared with lowest tertile (adjusted OR = 0.72, 95% CI: 0.53, 0.99) and (RR ratio = 0.62, 95% CI: 0.39, 1.00), respectively. However, these associations were attenuated by the prepregnancy BMI. No significant associations were observed between prepregnancy dietary patterns and LBW. Conclusion: This study suggests that better adherence to the traditional vegetables pattern before pregnancy is associated with a lower risk of preterm birth, particularly spontaneous preterm birth among nulliparous women. This finding warrants further examination.