Occupational exposure to inorganic particles during pregnancy and birth outcomes: a nationwide cohort study in Sweden

Abstract

ObjectivesThe aim of this study was to investigate if occupational exposure to inorganic particles or welding fumes during pregnancy is associated with negative birth outcomes.DesignA prospective national cohort study.SettingAll single births from 1994 to 2012 in Sweden. Information on birth weight, preterm birth, small for gestational age, smoking habits, nationality, age, occupation, absence from work and education was obtained from nationwide registers. Exposure to inorganic particles (mg/m3) was assessed from a job exposure matrix.ParticipantsThis study included all single births by occupationally active mothers (995 843).Outcome measuresAssociations between occupational exposures and negative birth outcomes in the form of low birth weight, preterm birth and small for gestational age.ResultsMothers who had high exposure to inorganic particles and had less than 50 days (median) of absence from work during pregnancy showed an increased risk of preterm birth (OR 1.18; 95% CI 1.07 to 1.30), low birth weight (OR 1.32; 95% CI 1.18 to 1.48) as well as small for gestational age (OR 1.20; 95% CI 1.04 to 1.39). The increased risks were driven by exposure to iron particles. No increased risks were found in association with exposure to stone and concrete particles. High exposure to welding fumes was associated with an increased risk of low birth weight (OR 1.22; 95% CI 1.02 to 1.45) and preterm birth (OR 1.24; 95% CI 1.07 to 1.42).ConclusionsThe results indicate that pregnant women should not be exposed to high levels of iron particles or welding fumes.

Mild steel and stainless steel welding fumes elicit pro‐inflammatory and pro‐oxidant effects in first trimester trophoblast cells

“…Several studies have already shown that maternal exposure to ultrafine particles in ambient air pollution is associated with adverse reproductive outcomes such as being born preterm, being small for gestational age, and fetal demise . Fewer studies exist on the association between occupational exposure to particles and adverse pregnancy outcomes, despite the fact that pollutant concentration in the workplace can be significantly higher than that of the outdoor environment …”

“…[50][51][52] Fewer studies exist on the association between occupational exposure to particles and adverse pregnancy outcomes, despite the fact that pollutant concentration in the workplace can be significantly higher than that of the outdoor environment. 53 Nanoparticles can directly affect fetal development by crossing the placental barrier and inducing oxidative stress and inflammation in F I G U R E 6 Significant production of IL-6 and IL-8 was observed in cells exposed to GMAW-MS. the fetus. 54,55 They can also indirectly harm the developing fetus as a result of maternal inflammation caused by nanoparticle exposure.…”

“…They can also indirectly harm the developing fetus as a result of maternal inflammation caused by nanoparticle exposure . Norlén et al recently published a prospective study that studied children born in Sweden between 1994 and 2012, whose mothers were occupationally exposed to inorganic particles such as iron dust or fumes as a result of welding, smelting, grinding, or other processing of steel and other materials containing iron. They found, that in mothers who did not have a high absence from work, and who were also exposed to iron‐containing particles throughout their gestation, there were statistically significant increased risks for babies being born small for gestational age, low birth weight, or preterm.…”

Occupational exposure to whole-body vibrations and pregnancy complications: a nationwide cohort study in Sweden

“…The Fetal Air Pollution Exposure cohort was formed by merging multiple Swedish national registers, and contains information regarding all registered births between 1994 and 2014 (n=2 113 336). 22 The Medical Birth Register has a 98%–99% coverage and contains data regarding, for example, maternal age, height, weight, occupation, smoking habits, parity and country of birth, which is collected at the first visit to the prenatal care clinics (usually around gestational week 10). 23 The register also has information on diagnoses during pregnancy.…”

“…Exposure to combustion particles was also based on measurements from different work places, and was in this study expressed as yes/no based on exposure to asphalt, diesel, polycyclic aromatic hydrocarbons, lead and/or other combustion particles. 22 For job strain and physically strenuous work, an index with scores from 1 to 6 and 1-10, respectively, was calculated based on answers from the work environment survey performed by the Swedish Work Environment Authority every other year. 14 The survey is sent to a sample of the working population (ages 16-74, n≈4000-12 000) and includes questions regarding control and demands (job strain), as well as turning, lifting, bending, heavy breathing, working with hands above the head or with heavy objects, and repeated movements (physically strenuous work).…”