Objective: To estimate the distribution and success of programmed fetal growth phenotypes among obese women.
Methods: This was a retrospective cohort study using the Missouri maternally linked cohort files (years 1978-1997). Maternal body mass index was classified as Normal (18.5-24.9) (referent group), Obese (class 1, 30.0-34.9; class 2, 35.0-39.9; and extreme or class 3, 40 or more). Fetal growth phenotypes were defined as large for gestational age (LGA), appropriate for gestational age (AGA), and small for gestational age (SGA). We used adjusted odds ratio with correction for intracluster correlation to estimate the risk of neonatal mortality for each fetal growth phenotype.
Results: As compared with normal weight mothers, obese gravidas tended to program LGA infants at a higher and increasing rate with ascending obesity severity. The opposite effect was observed with respect to AGA and SGA programming patterns. Neonatal mortality among LGA infants was similar for obese (6.2 in 1,000) and normal (4.9 in 1,000) weight mothers (OR 1.05, 95% confidence interval [CI] 0.75-1.48) and regardless of obesity subtype. By contrast, SGA and AGA infants programmed by obese mothers experienced greater neonatal mortality as compared with those born to normal weight mothers (AGA OR 1.45, 95% CI 1.32-1.59; SGA OR 1.72, 95% CI 1.49-1.98).
Conclusion: Compared with normal weight mothers, obese women are least successful at programming SGA, less successful at programming AGA, and equally as successful at programming LGA infants.
Level of evidence: II.