Prenatal exposure to insecticides and child weight trajectories in a South African birth cohort
Bibliographic record
Abstract
Background: DDT or pyrethroid insecticides are sprayed inside dwellings as part of global malaria vector control programs, resulting in high levels of exposure to millions of people, including pregnant women. These chemicals are endocrine disruptors and may affect child growth. Study Design: The Venda Health Examination of Mothers, Babies and their Environment (VHEMBE) is a birth cohort study based in Limpopo, South Africa (n=752). Maternal peripartum concentrations of DDT and its breakdown product DDE were measured in serum and pyrethroid metabolites were measured in urine. Child weight was measured at birth and at 1, 2, 3.5 and 5-year follow-up visits; weight measurements were also abstracted from medical records. Methods: We modelled child weight trajectories using SuperImposition, Translation and Rotation (SITAR) to estimate child-specific weight over time and age at peak weight velocity (APWV). We then estimated associations between insecticides and SITAR parameters using multivariable linear regression. We also investigated whether child sex and maternal energy intake sufficiency during pregnancy modified these associations. Results: Maternal p,p’-DDT was associated with greater weight among girls (β=14g per 10-fold increase; 95%CI=0, 28) and children of mothers with sufficient energy intake (β=18g per 10-fold increase; 95%CI=1, 35). We also found that pyrethroids may be associated with lower weight and earlier APWV among boys, particularly for cis-DBCA, which is specific to deltamethrin (βweight= -24g per 10-fold increase; 95%CI=-52, 4; βAPWV=-2.6 days per 10-fold increase; 95% CI: -5.3, 0.1). Conclusions: Maternal DDT and pyrethroid exposure may be associated with child growth through age 5. Positive associations between p,p’-DDT and weight among girls are consistent with its estrogenic properties, and inverse associations between pyrethroids and weight and APWV among boys may be related to their androgenic properties. These findings, as well as that of effect modification by maternal energy intake, support our previous research in this population.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".