Objective We aimed to study multiple occupational exposures selected using an priori hypothesis as well as small-for-gestational age (SGA), birthweight (BW), and head circumference (HC).

Methods We analyzed data from the Étude Longitudinale Française depuis l`Enfance (ELFE) cohort (N=12 851 mother-child pairs with a gestational age >33 weeks). The outcomes of interest were SGA, BW, and HC. Of 47 factors (17 chemical, 8 physical, 4 biological, 12 biomechanical, 3 organizational and 3 psychosocial) to which mothers were exposed in their occupation assessed by job-exposure matrices in this cohort, we included those for which the epidemiological or experimental literature suggests an association with fetal growth. Logistic and linear regression models that included all preselected exposure variables were performed and adjusted for potential confounders. We conducted additional analysis stratified by trimester of pregnancy.

Results The logistic model, which included all preselected variables, reported that – for all women – exposure to ultrafine particles (UFP) increased SGA risk [odds ratio (OR) 1.46, 95% confidence interval (CI) 1.12–1.90] while standing decreased it (OR 0.82, 95% CI 0.67–1.00). Among mothers who stopped working during the first/second trimester of pregnancy, we found the same SGA risk for UFP; exposure to high strain also increased the risk (OR 1.81, 95% CI 1.18–2.83). Among those who stopped working during the third trimester, exposure to oxygenated solvents increased SGA risk (OR 2.24, 95% CI 1.08–4.41). In the linear model, for all women, there was a decrease in BW (β -34 grams, 95% CI -66– -1.1) among those exposed to UFP. For mothers who stopped working during the first/second trimester, exposure to vibration increased BW, while among those who stopped working during the third trimester, exposure to night work increased BW. Exposure to oxygenated solvents decreased HC (β -0.22 cm, 95% CI -0.44–0.00) among all women.

Conclusion These findings suggest the possible influence of chemical and strenuous factors at work on fetal growth, particularly depending on the trimester in which pregnant mothers stopped working. While the combined assessment of multiple exposures did not reveal clear associations, further studies are needed to explore potential interactions and underlying biological mechanisms.

Key terms children; ELFE; exposure; fetal growth; hypothesis-driven; longitudinal study; maternal occupational exposure; newborn size; pregnancy; pregnant worker