Examining the role of pre-pregnancy weight and gestational weight gain in allergic disease development among offspring: A population-based cohort study in Ontario, Canada

Maternal obesity and childhood asthma risk: Exploring mediating pathways

BACKGROUND

Growing evidence for the effect of maternal obesity on childhood asthma motivates investigation of mediating pathways.

OBJECTIVE

To investigate if childhood body mass index (BMI), gestational weight gain (GWG) and preterm birth mediate the association of maternal obesity on childhood asthma risk.

METHODS

We used electronic medical records from mother-child pairs enrolled in Kaiser Permanente Northern California integrated healthcare system. Children were followed from their birth (2005-2014) until at least age 4 (n = 95,723), age 6 (n = 59,230) or age 8 (n = 25,261). Childhood asthma diagnosis at each age was determined using ICD-9/10 codes and medication dispensings. Prepregnancy BMI (underweight [<18.5], normal [18.5-24.9], overweight [25-29.9], obese [≥30] kg/m2) were defined using height and weight measurements close to the last menstrual period date. Child's BMI (Centers for Disease Control and Prevention BMI-for-age percentiles: underweight [<5th], normal [5th-85th], overweight [85th-95th], obese [>95th]) were obtained using anthropometric measurements taken the year preceding each follow-up age. GWG (delivery weight-prepregnancy weight) was categorised based on Institutes of Medicine recommendations (inadequate, adequate, excessive). Implementing first causal inference test (CIT) then causal mediator models (to decompose the natural direct and indirect effects), we examined the potential mediating effect of childhood BMI, GWG, and preterm birth on the association between prepregnancy BMI (continuous and categorical) and childhood asthma.

RESULTS

Overall, risk of childhood asthma increased as prepregnancy BMI increased (age 4 risk ratio: 1.07, 95% confidence interval: 1.04, 1.09, per 5 kg/m2 increase in BMI; similar for age 6 and 8). CIT identified childhood BMI and preterm birth, but not GWG as potential mediators. Causal mediation models confirmed childhood BMI, but not preterm birth, as having a partial mediating effect. Results were similar for age 6 and 8, and when continuous mediators (instead of binary) were assessed.

CONCLUSIONS

Childhood overweight/obesity has a modest mediating effect on the association between prepregnancy BMI and childhood asthma.

Maternal prepregnancy body mass index, gestational weight gain, and allergic diseases in children: A systematic review and meta-analysis

Several studies have investigated a link between maternal preconception body mass index, gestational weight gain (GWG), and the risk of childhood allergic diseases, but the conclusions of these studies were inconsistent. This review aimed to evaluate the relationship based on existing studies. We eventually included 18 cohort studies. The findings indicated that both maternal preconception overweight or obesity increased the risk of childhood wheezing (overweight: risk ratio (RR) 1.09, 95% confidence interval (CI) 1.04-1.15; obesity: RR 1.24, 95% CI 1.12-1.38) and asthma (overweight: RR 1.18, 95% CI 1.05-1.32; obesity: RR 1.34, 95% CI 1.13-1.58), and the risk of childhood wheezing increased with continuous prepregnancy BMI changes (per 5 kg/m2 increase) (RR 1.10, 95% CI 1.05-1.15). Preconception underweight may elevate the risk of childhood eczema ever (RR 1.05, 95% CI 1.02-1.09) and current eczema (RR 1.20, 95% CI 1.05-1.37), and preconception overweight may reduce the risk of childhood eczema ever (RR 0.98, 95% CI 0.96-0.99). No statistically significant association between GWG and the risk of allergic diseases in children was found. Preconception weight management is encouraged for the prevention of allergic diseases in children.

Cohort Study of Maternal Gestational Weight Gain, Gestational Diabetes, and Childhood Asthma

Data on the association of maternal gestational weight gain (GWG) and gestational diabetes mellitus (GDM) with childhood asthma are limited and inconsistent. We aimed to investigate these associations in a U.S. pre-birth cohort. Analyses included 16,351 mother-child pairs enrolled in the Massachusetts General Hospital Maternal-Child Cohort (1998-2010). Data were obtained by linking electronic health records for prenatal visits/delivery to determine BMI, GWG, and GDM (National Diabetes Data Group criteria) and to determine asthma incidence and allergies (atopic dermatitis or allergic rhinitis) for children. The associations of prenatal exposures with asthma were evaluated using logistic regression adjusted for maternal characteristics. A total of 2306 children (14%) developed asthma by age 5 years. Overall, no association was found between GWG and asthma. GDM was positively associated with offspring asthma (OR 1.46, 95% CI 1.14-1.88). Associations between GDM and asthma were observed only among mothers with early pregnancy BMI between 20 and 24.9 kg/m² (OR 2.31, CI 1.46-3.65, p-interaction 0.02). We report novel findings on the impact of prenatal exposures on asthma, including increased risk among mothers with GDM, particularly those with a normal BMI. These findings support the strengthening of interventions targeted toward a healthier pregnancy, which may also be helpful for childhood asthma prevention.

Prepregnancy body mass index and risk of childhood asthma

BACKGROUND

Growing evidence suggests that maternal obesity may affect the intrauterine environment and increase a child's risk of developing asthma. We aim to investigate the relationship between prepregnancy obesity and childhood asthma risk.

METHODS

Cohorts of children enrolled in Kaiser Permanente Northern California integrated healthcare system were followed from birth (2005-2014) to age 4 (n = 104,467), 6 (n = 63,084), or 8 (n = 31,006) using electronic medical records. Child's asthma was defined using ICD codes and asthma-related prescription medication dispensing. Risk ratios (RR) and 95% confidence intervals (95% CIs) for child's asthma were estimated using Poisson regression with robust error variance for (1) prepregnancy BMI categories (underweight [<18.5], normal [18.5-24.9], overweight [25-29.9], obese 1 [30-34.9], and obese 2/3 [≥35]) and (2) continuous prepregnancy BMI modeled using cubic splines with knots at BMI category boundaries. Models were adjusted for maternal age, education, race, asthma, allergies, smoking, gestational weight gain, child's birth year, parity, infant sex, gestational age, and child's BMI.

RESULTS

Relative to normal BMI, RRs (95%CIs) for asthma at ages 4, 6, and 8 were 0.91 (0.75, 1.11), 0.95 (0.78, 1.16), and 0.97 (0.75, 1.27) for underweight, 1.06 (0.99, 1.14), 1.08 (1.01, 1.16), and 1.03 (0.94, 1.14) for overweight, 1.09 (1.00, 1.19), 1.12 (1.03, 1.23), 1.03 (0.91, 1.17) for obese 1, and 1.10 (0.99, 1.21), 1.13 (1.02, 1.25), 1.14 (0.99, 1.31) for obese 2/3. When continuous prepregnancy BMI was modeled with splines, child's asthma risk generally increased linearly with increasing prepregnancy BMI.

CONCLUSIONS

Higher prepregnancy BMI is associated with modestly increased childhood asthma risk.

Prepregnancy overweight and obesity as risk factors for birth defects: a cross-sectional study over a 30-year period

Overweight and obesity are public health problems worldwide despite being modifiable conditions. The association between birth defects and pregestational maternal body mass index is not entirely clear. We aimed to assess the prevalence and estimate the risk of birth defects related to pregestational body mass index and other maternal factors. We explored a 30-year time series database in a cross-section study. We analysed 40,217 cases, among them 2.8% had birth defects. Bivariate analysis showed a higher prevalence of birth defects with increased pre-pregnancy body mass index and in extremes of maternal age, white skin colour, and primiparity. Multivariable logistic regression showed a higher chance of birth defects in women with pre-pregnancy overweight/obesity (OR:1.19 [CI95%:1.01-1.41]), maternal age ≥ 40 years (OR:1.68 [CI95%:1.11-2.54]), and white skin colour (OR:1.44 [CI95%:1.19-1.75]). Maternal weight is a modifiable risk factor that must be considered and addressed in preconception counselling to minimise possible deleterious effects on embryogenesis.IMPACT STATEMENTWhat is already known on this subject? Previous studies have linked some maternal factors with birth defects. However, the association with prepregnancy maternal body mass index is not clear.What do the results of this study add? Our findings provide support for the association of prepregnancy maternal overweight and obesity with birth defects and highlight that BMI is a modified risk factor.What are the implications of these findings for clinical practice and/or further research? Maternal body mass index is a modifiable risk factor, highlighting the importance of preconception counselling for the prevention and possible reduction of factors that increase the risk of birth defects.

Maternal obesity, gestational weight gain, and offspring asthma and atopy

BACKGROUND

Maternal obesity may affect offspring asthma and atopic disease risk by altering fetal immune system development. However, few studies evaluate gestational weight gain (GWG).

OBJECTIVE

To evaluate relationships between maternal body mass index (BMI), GWG, and persistent wheeze, eczema, allergy, and asthma risk in offspring through middle childhood.

METHODS

A total of 5939 children from Upstate KIDS, a population-based longitudinal cohort of children born in upstate New York (2008-2019) were included in the analysis. Persistent wheeze or asthma, eczema, and allergy were maternally reported at multiple study time points throughout early and middle childhood. Poisson regression models with robust SEs were used to estimate adjusted risk ratios (aRRs) and 95% confidence intervals (CIs) for offspring atopic outcomes by maternal prepregnancy BMI and GWG.

RESULTS

Prepregnancy BMI was associated with increased risk of persistent wheeze by 3 years of age even after adjustments for maternal atopy (class I obesity: aRR, 1.58; 95% CI, 1.13-2.20; class II or III obesity: aRR, 1.69; 95% CI, 1.22-2.35). Associations with reported asthma in middle childhood did not reach statistical significance. Furthermore, no associations were found between prepregnancy BMI and atopic outcomes in either early or middle childhood. GWG was not associated with higher risk of early childhood persistent wheeze or middle childhood asthma.

CONCLUSION

Maternal prepregnancy BMI was associated with increased risk of offspring wheeze, whereas excessive GWG was generally not associated with childhood asthma or atopy.