The Relationship of Maternal Prepregnancy Body Mass Index and Pregnancy Weight Gain to Neurocognitive Function at Age 10 Years among Children Born Extremely Preterm

Abstract

Objective: To assess the association between maternal prepregnancy body mass index and adequacy of pregnancy weight gain in relation to neurocognitive function in school-aged children born extremely preterm.

Study design: Study participants were 535 ten-year-old children enrolled previously in the prospective multicenter Extremely Low Gestational Age Newborns cohort study who were products of singleton pregnancies. Soon after delivery, mothers provided information about prepregnancy weight. Prepregnancy body mass index and adequacy of weight gain were characterized based on this information. Children underwent a neurocognitive evaluation at 10 years of age.

Results: Maternal prepregnancy obesity was associated with increased odds of a lower score for Differential Ability Scales-II Verbal IQ, for Developmental Neuropsychological Assessment-II measures of processing speed and visual fine motor control, and for Wechsler Individual Achievement Test-III Spelling. Children born to mothers who gained an excessive amount of weight were at increased odds of a low score on the Oral and Written Language Scales Oral Expression assessment. Conversely, children whose mother did not gain an adequate amount of weight were at increased odds of a lower score on the Oral and Written Language Scales Oral Expression and Wechsler Individual Achievement Test-III Word Reading assessments.

Conclusion: In this cohort of infants born extremely preterm, maternal obesity was associated with poorer performance on some assessments of neurocognitive function. Our findings are consistent with the observational and experimental literature and suggest that opportunities may exist to mitigate risk through education and behavioral intervention before pregnancy.

Keywords: extremely preterm infants; maternal pre-pregnancy BMI; maternal weight gain; neurocognitive function.

Figure 1

Forest plots of odds ratios (ORs) and 95% confidence intervals of a Z-score ≤ −1 on each Differential Ability Scales-II (DAS-II), Oral and Written Language Scales (OWLS), Developmental Neuropsychological Assessment-II (NEPSY-II), or Wechsler Individual Achievement Test-III (WIAT-III) assessment at age 10 associated with maternal pre-pregnancy BMI < 18.5 (left panel), ≥ 25, < 30 (middle panel) and BMI ≥ 30 (right panel) relative to BMI 18 – < 25. Odds ratios in the top panel are unadjusted while those in the bottom panel are adjusted for maternal race, education and public insurance. Verbal IQ, Nonverbal IQ, and Working Memory are derived from the DAS-II. Listening Comprehension and Oral Expression are derived from the OWLS. Auditory Attention, Auditory Response Set, Inhibition Inhibition, Animal Sorting, Inhibition Naming, Arrows, Geometric Puzzles, and Visuomotor Precision are derived from the NEPSY-II. Word Reading, Pseudoword Decoding, Spelling, and Numerical Operations are derived from the WIAT-II.

Figure 2

Forest plots of odds ratios (ORs) and 95% confidence intervals of a Z-score ≤ −1 on each Differential Ability Scales-II (DAS-II), Oral and Written Language Scales (OWLS), Developmental Neuropsychological Assessment-II (NEPSY-II), or Wechsler Individual Achievement Test-III (WIAT-III) assessment at age 10 associated with inadequate (left panel) and excessive (right panel) maternal pregnancy weight gain relative to adequate pregnancy weight gain. Odds ratios in the top panel are unadjusted while those in the bottom panel are adjusted for maternal race, education, public insurance, and prepregnancy BMI. Verbal IQ, Nonverbal IQ, and Working Memory are derived from the DAS-II. Listening Comprehension and Oral Expression are derived from the OWLS. Auditory Attention, Auditory Response Set, Inhibition Inhibition, Animal Sorting, Inhibition Naming, Arrows, Geometric Puzzles, and Visuomotor Precision are derived from the NEPSY-II. Word Reading, Pseudoword Decoding, Spelling, and Numerical Operations are derived from the WIAT-II.

Figure 3

Scatterplots depicting the relationship of maternal pre-pregnancy BMI to Z-scores for neurocognitive outcomes. The vertical line indicates BMI > 30.