Development of a quantitative job exposure matrix for standing, walking, and forward bending among pregnant workers – The PRECISE JEM

TL;DR

This paper creates a detailed job exposure matrix to assess physical activity levels in pregnant workers, aiming to improve understanding of how occupational activities affect pregnancy outcomes.

Contribution

The study introduces a trimester-specific job exposure matrix for standing, walking, and forward bending among pregnant workers using objective measurements.

Findings

The JEM estimates exposure levels for 1171 job codes using accelerometer data and mixed-effects models.

Bakers had the highest standing exposure, while waiters and livestock producers had the highest walking and forward bending exposure, respectively.

Trimester-specific adjustments showed reduced standing time in the third trimester compared to non-pregnant workers.

Abstract

Occupational physical activity (OPA) during pregnancy has been linked to adverse pregnancy outcomes, but crude exposure assessment remains an issue in causal inference. We aimed to develop a quantitative trimester-specific job exposure matrix (JEM) for standing, walking, and forward bending among pregnant workers.

Accelerometer measurements from 403 female workers across 109 DISCO-08 job codes were obtained in Denmark between January 2023 and June 2024. Full workdays were measured during two weeks among pregnant workers and one week among non-pregnant workers. We used linear mixed-effects models to estimate exposure levels of occupational standing, walking, and forward bending for all 1171 DISCO-08 codes, including age, trimester, and expert ratings as fixed effects, and job codes and workers as random effects.

The between-job variances relative to total variances were 56% for standing, 51% for walking, and 45% for forward bending. The fixed effect trimester reduced standing time by 0.38 hours during the 3rd trimester compared to non-pregnant participants, whereas no differences were observed for walking or forward bending. Based on the trimester-specific JEM for occupational standing time, bakers had the highest exposure (range from non-pregnant to 3rd trimester, 5.41–5.03 hours/workday). For walking and forward bending, the highest exposed jobs from the pregnancy-specific JEM were waiters (1.76 hours/workday) and livestock/dairy producers (1.24 hours/workday), respectively.

The JEM enhances independent objective exposure assessment in epidemiological studies of OPA and pregnancy outcomes and may advance guidelines and potentially prevent adverse pregnancy outcomes.

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