Associations of Maternal Educational Level, Proximity to Green Space During Pregnancy, and Gestational Diabetes With Body Mass Index From Infancy to Early Adulthood: A Proof-of-Concept Federated Analysis in 18 Birth Cohorts

Abstract

International sharing of cohort data for research is important and challenging. We explored the feasibility of multicohort federated analyses by examining associations between 3 pregnancy exposures (maternal education, exposure to green vegetation, and gestational diabetes) and offspring body mass index (BMI) from infancy to age 17 years. We used data from 18 cohorts (n = 206,180 mother-child pairs) from the EU Child Cohort Network and derived BMI at ages 0-1, 2-3, 4-7, 8-13, and 14-17 years. Associations were estimated using linear regression via 1-stage individual participant data meta-analysis using DataSHIELD. Associations between lower maternal education and higher child BMI emerged from age 4 and increased with age (difference in BMI z score comparing low with high education, at age 2-3 years = 0.03 (95% confidence interval (CI): 0.00, 0.05), at 4-7 years = 0.16 (95% CI: 0.14, 0.17), and at 8-13 years = 0.24 (95% CI: 0.22, 0.26)). Gestational diabetes was positively associated with BMI from age 8 years (BMI z score difference = 0.18, 95% CI: 0.12, 0.25) but not at younger ages; however, associations attenuated towards the null when restricted to cohorts that measured gestational diabetes via universal screening. Exposure to green vegetation was weakly associated with higher BMI up to age 1 year but not at older ages. Opportunities of cross-cohort federated analyses are discussed.

Keywords: BMI; cohort data sharing; federated analyses; gestational diabetes; green spaces; maternal education.

Figure 1

Flow chart of cohorts and participants for a study of associations of maternal educational level, proximity to green space during pregnancy, and gestational diabetes with body mass index (BMI) from infancy to early adulthood, multiple countries. Signed agreements received and DataSHIELD access credentials provided. HBCS, Helsinki Birth Cohort Study.

Figure 2

Exposure descriptive statistics for a study of associations of maternal educational level, proximity to green space during pregnancy, and gestational diabetes with body mass index (BMI) from infancy to early adulthood, multiple countries. A) Maternal education: dark blue = low education, teal = medium education, yellow = high education, orange = missing. B) Normalized difference vegetation index (NDVI). C) Gestational diabetes: dark blue = no pregnancy diabetes, teal = pregnancy diabetes, orange = missing. No data was available on gestational diabetes for the EU Childhood Obesity Programme (CHOP) as this was an exclusion criterion for entry into the study. For all other studies, figures are blank where the exposure is entirely missing. Values for NDVI represent median and interquartile range. All the study names are defined in Table 1, and descriptions of all the cohorts can be found in Web Appendix 2. Data was included from cohorts containing births from years 1966--2016.

Figure 3. Associations between maternal education at birth and child body mass index z scores using 1-stage individual patient data meta-analysis of data from multiple countries, from cohorts containing births from years 1966--2016. Models adjusted for cohort, child sex, and exact age at measurement in days. Solid fill = maximum available sample; no fill = restricted to sample with available data at ages 14–17 years. BMI, body mass index.

Figure 4. Associations between normalized difference vegetation index in pregnancy and child body mass index z scores using 1-stage individual patient data meta-analysis of data from multiple countries, from cohorts containing births from years 1966--2016. Models adjusted for cohort, child sex, exact age at measurement, maternal education, parity, and area deprivation. Normalized difference vegetation index scaled by interquartile range. Solid fill = maximum available sample; no fill = restricted to sample with available data at ages 14–17 years. BMI, body mass index.

Figure 5. Associations between gestational diabetes and child body mass index z scores using 1-stage individual patient data meta-analysis of data from multiple countries, from cohorts containing births from years 1966--2016. Models adjusted for cohort, child sex, exact age at measurement, maternal education, maternal age at birth, prepregnancy body mass index (BMI), pregnancy smoking, and parity. Solid fill = maximum available sample; no fill = restricted to sample with available data at ages 14–17.