# The contribution of maternal glucose to birth weight is smaller in Uganda (sub-Saharan Africa) than in Afro-Caribbean or white ethnicity mother–child pairs from outside Africa

## TL;DR

This study finds that maternal glucose levels have a smaller impact on birth weight in Uganda compared to Afro-Caribbean and white populations, suggesting the need for region-specific guidelines.

## Contribution

The study provides novel evidence on ethnic and regional differences in the relationship between maternal glucose and birth outcomes in sub-Saharan Africa.

## Key findings

- Maternal fasting glucose contributes less to birth weight in Uganda than in Afro-Caribbean or white populations.
- The risk of large for gestational age births is lower in Uganda at similar glucose levels compared to other regions.
- Glycaemia's effect is consistent using fasting, 1-hour, or 2-hour glucose measures in the study.

## Abstract

Glucose is a major determinant of fetal growth, but its relative contribution in different ethnic groups or populations is not fully understood. The Hyperglycaemia and Adverse Pregnancy Outcome (HAPO) Study established a relationship between glucose and birth weight in multiple ethnic groups. However, the HAPO Study did not include any cohorts from sub-Saharan Africa (SSA), where 17% of the world population lives. This study aims to address this in a cohort study from Uganda.

We compared the relationship between oral glucose tolerance test measures and fetal outcomes in participants from Uganda (n=2544), Afro-Caribbean participants in HAPO (n=1224) and white participants in HAPO (n=7679). We used multivariable linear regression to assess the correlation between birth weight adjusted for gestational age and sex with maternal glucose concentration. Logistic regression was used to determine the association of large for gestational age (LGA) (defined as birthweight >90th percentile) with maternal fasting glucose.

The contribution of maternal fasting glucose to birth weight was substantially lower in Uganda than in other settings: β-coefficient (95% CI) 104 (58.6 to 149) g/mmol/L in Uganda, 203 (137 to 270) g/mmol/L HAPO-Afro-Caribbean (AFC) and 239 (214 to 265) g/mmol/L HAPO-white. Likewise, the risk of LGA with higher fasting glucose was smaller in Uganda compared with the HAPO cohorts (adjusted OR (95% CI) 1.13 (1.00 to 1.29) in Uganda, 1.38 (1.15 to 1.66) HAPO-AFC, and 1.57 (1.46 to 1.69) HAPO-white. The contribution of glycaemia was similar using 1-hour and 2-hour post-glucose load concentrations in place of fasting glucose.

The contribution of maternal glucose to birth weight and the risk of LGA at a given level of hyperglycaemia is substantially lower in SSA than in populations in the HAPO study. These data support the need for locally derived glycaemia cut-offs to identify women at risk of adverse pregnancy outcomes in SSA.