Validity of Parent-Reported Gestational Age Categories and Association Between Total Gestational Weight Gain by Pre-pregnancy Body Mass Index and Moderate to Late Preterm Birth

Abstract

BACKGROUND: Gestational age is influenced by several factors; however, the impact of total gestational weight gain (GWG) on moderate to late preterm birth (32-<37 weeks) is less understood.

OBJECTIVES: To evaluate the validity of parent-reported gestational age categories relative to administrative healthcare data. To evaluate the association between total GWG and moderate to late preterm birth.

METHODS: Data analysis was conducted from children <6 years of age in the Toronto area enrolled in TARGet Kids!, a primary care-based pediatric research network. First, I conducted a validation study (n=4684) using linked data from TARGet Kids! and healthcare administrative data to assess the criterion validity of questionnaire-based parent-reported term (≥37 weeks), late preterm (34-36 weeks), and moderately preterm (32-33 weeks) birth. Second, I conducted a cross-sectional study (n=4529) using TARGet Kids! data to assess the association between total GWG and moderate to late preterm birth. GWG was categorized according to the Institute of Medicine (IOM) guidelines as inadequate, recommended, or excessive for each pre-pregnancy BMI category. Continuous GWG was also assessed.

RESULTS: 97.3% correctly classified their child’s gestational age according to administrative data. Sensitivity was >80% and specificity was >85%. 31.1% of maternal parents had recommended GWG; 41.0% had excessive GWG and 27.9% had inadequate GWG. 8.2% of births were moderate to late preterm. Excessive GWG was strongly associated with moderate to late preterm birth (aOR 1.68; 95% CI 1.29, 2.19). For maternal parents with pre-pregnancy overweight or obesity, the risk of preterm birth did not increase substantially until well beyond the upper limit of the IOM guidelines.

CONCLUSIONS: Parent-reported gestational age was accurate. The IOM total GWG recommendations may not align with the lowest risk of preterm birth for maternal parents with pre-pregnancy overweight or obesity. Future research should re-evaluate the recommendations, particularly among those with overweight or obesity pre-pregnancy.