Association of maternal gestational weight gain with intellectual developmental disorder in the offspring: a nationwide follow-up study in Sweden

Objectives To investigate the association between maternal gestational weight gain (GWG) and offspring's intellectual developmental disorders (IDD); how this association is modified by maternal early-pregnancy BMI. Design Population-based cohort study. Setting and population All liveborn singletons with information on maternal GWG in the Swedish Medical Register during 1992-2006 (n = 467 485). Methods We used three GWG classifications, (1) Institute of Medicine (IOM) guidelines ('ideal' GWG: maternal underweight = 12.7-18.1 kg; normal = 11.3-15.9 kg; overweight = 6.8-11.3 kg; obesity = 5.0-9.1 kg), (2) LifeCycle project recommendation ('ideal' GWG: maternal underweight = 14.0-16.0 kg; normal = 10.0-18.0 kg; overweight = 2.0-16.0 kg; obesity class I = 2.0-6.0 kg; obesity class II <= 0.0-4.0 kg; obesity class III <= 0.0-6.0 kg) and (3) GWG centiles. Hazard ratio (HR) and 95% CI for offspring's IDD risk using Cox regression. Main outcome measures IDD was extracted from Swedish National Patient Register (code ICD-9:317-319/ICD-10:F70-F79). Results Forty-one per cent of children were born to mothers with excessive GWG, 32.8% with ideal GWG and 26.2% with inadequate GWG according to IOM guidelines. Inadequate GWG was associated with 21% higher risk of offspring's IDD (95% CI 1.11-1.31) relative to ideal GWG. In contrast, when using the LifeCycle classification, children of mothers with inadequate GWG (HR 1.14, 95% CI 1.05-1.24) or excessive GWG (HR 1.09, 95% CI 1.01-1.17) had higher risks of IDD than those of mothers with ideal GWG. When using GWG centiles, extremely low GWG (<20th centile) and low GWG (20th-40th centile) were associated with elevated offspring's IDD risk. Further stratified analysis by maternal early-pregnancy body mass index (BMI) showed that overweight/obese mothers (BMI >= 25 kg/m(2)) with extremely excessive GWG (>25 kg) was associated with an increased offspring's IDD. Conclusion Our findings suggest that inadequate maternal GWG may increase offspring's IDD risk, irrespective of maternal early-pregnancy BMI. Extremely excessive GWG (>25 kg) may increase offspring's IDD risk, but only among mothers with an early-pregnancy BMI >= 25 kg/m(2). Tweetable abstract Inadequate maternal weight gain during pregnancy may increase the risk of offspring's intellectual disability, regardless of maternal BMI.

Automated summary

The study found an association between maternal gestational weight gain and offspring's intellectual developmental disorders, which may be modified by maternal early-pregnancy BMI.