Assessed occupational exposure to chlorinated, aromatic and Stoddard solvents during pregnancy and risk of fetal growth restriction

Maternal occupational exposure to selected organic and chlorinated solvents and delivery of small-for-gestational age or preterm infants

BACKGROUND

Potential reproductive effects of organic solvent exposure during pregnancy remain unclear. We investigated the association between maternal occupational exposure during pregnancy to six chlorinated solvents, three aromatic solvents, and Stoddard solvent, and delivery of preterm infants or those born small-for-gestational age (SGA).

METHODS

In this case-control study of SGA and preterm birth (PTB) nested within the National Birth Defects Prevention Study (NBDPS) from 1997 to 2011, we analyzed data from 7504 singleton live births without major birth defects and their mothers. Self-reported information on jobs held in the periconceptional period was assessed for solvent exposure. Unconditional logistic regression was used to estimate the association between maternal occupational exposure (any, none) during early pregnancy to organic solvents and PTB and SGA. Linear regression was used to examine changes in mean birthweight potentially associated with maternal occupational solvent exposure.

RESULTS

Maternal occupational exposure to any organic solvents overall was not associated with an increased odds of PTB (adjusted odds ratio [aOR] = 0.94; 95% confidence interval [CI] 0.67-1.33) or SGA (aOR = 0.93; 95% CI 0.65-1.34). Point estimates increased modestly for higher estimated exposure versus lower, but confidence intervals were wide and not statistically significant. Maternal exposure to solvents was not associated with a statistically significant change in term birthweight among infants.

CONCLUSIONS

Occupational exposure to organic solvents at the frequency and intensity levels found in a population-based sample of pregnant workers was not associated with PTB or SGA; however, we cannot rule out any effects among pregnant workers with uncommonly high exposure to organic solvents.

Maternal occupational exposure to organic solvents and intrauterine growth in the ELFE cohort

BACKGROUND

In developed countries, about 15% of women are occupationally exposed to solvents. Associations between this maternal occupational exposure and intrauterine fetal growth are inconsistent, but almost no existing study has investigated this relation by solvent family (oxygenated, petroleum, and chlorinated), although they may affect fetal growth differently.

OBJECTIVES

To investigate the relations between maternal occupational solvent exposure, by solvent family, and the risk of neonates born small for gestational age (SGA), or with low birthweight, or with small head circumference (HC).

METHODS

Among the 18,040 women enrolled in the Elfe rather than included in the Elfe birth cohort, we included 13,026 women who worked during pregnancy (72% of the cohort). Information about maternal occupations and industrial activities during pregnancy was collected by questionnaire at the maternity ward, and completed at 2-month when necessary. Using Matgéné job-exposure matrices, we assessed maternal occupational exposure to solvents. Logistic and multiple linear regressions were used to assess the association between maternal occupational solvent exposure and SGA status, birth weight, and HC. Analyses were conducted for exposure during pregnancy and also stratified by the trimester that pregnancy leave began.

RESULTS

We observed a higher risk of SGA newborns among mothers occupationally exposed during pregnancy to petroleum solvents (OR_adjusted = 1.26; 95%CI: 1.01 to 1.57). Among women working until the third trimester of pregnancy, we observed a higher risk of SGA newborns to those occupationally exposed to oxygenated solvents (OR_adjusted = 1.75; 95%CI: 1.11 to 2.75), a significantly lower birthweight for infants of mothers exposed to petroleum solvents (β_adjusted = -47.37 g; -89.33 to -5.42), and a lower HC among newborns of those occupationally exposed to oxygenated solvents (β_adjusted = -0.28; -0.49 to -0.07) and to chlorinated solvents (β_adjusted = -0.29; -0.53 to -0.05).

DISCUSSION

Our results suggest that maternal occupational solvent exposure may influence fetal growth, especially exposure into the third trimester of pregnancy.

A Review on the Vagus Nerve and Autonomic Nervous System During Fetal Development: Searching for Critical Windows

The autonomic nervous system (ANS) is one of the main biological systems that regulates the body's physiology. Autonomic nervous system regulatory capacity begins before birth as the sympathetic and parasympathetic activity contributes significantly to the fetus' development. In particular, several studies have shown how vagus nerve is involved in many vital processes during fetal, perinatal, and postnatal life: from the regulation of inflammation through the anti-inflammatory cholinergic pathway, which may affect the functioning of each organ, to the production of hormones involved in bioenergetic metabolism. In addition, the vagus nerve has been recognized as the primary afferent pathway capable of transmitting information to the brain from every organ of the body. Therefore, this hypothesis paper aims to review the development of ANS during fetal and perinatal life, focusing particularly on the vagus nerve, to identify possible "critical windows" that could impact its maturation. These "critical windows" could help clinicians know when to monitor fetuses to effectively assess the developmental status of both ANS and specifically the vagus nerve. In addition, this paper will focus on which factors-i.e., fetal characteristics and behaviors, maternal lifestyle and pathologies, placental health and dysfunction, labor, incubator conditions, and drug exposure-may have an impact on the development of the vagus during the above-mentioned "critical window" and how. This analysis could help clinicians and stakeholders define precise guidelines for improving the management of fetuses and newborns, particularly to reduce the potential adverse environmental impacts on ANS development that may lead to persistent long-term consequences. Since the development of ANS and the vagus influence have been shown to be reflected in cardiac variability, this paper will rely in particular on studies using fetal heart rate variability (fHRV) to monitor the continued growth and health of both animal and human fetuses. In fact, fHRV is a non-invasive marker whose changes have been associated with ANS development, vagal modulation, systemic and neurological inflammatory reactions, and even fetal distress during labor.

Trends in Cigarette Smoking Prevalence Among Refinery and Petrochemical Plant Workers, 1950 to 1999

OBJECTIVE

Smoking is a potential confounder in studies of workplace exposures and smoking-related disease, but little data exist to quantitatively adjust for smoking in statistical models.

METHODS

We estimated smoking prevalence trends between 1950 and 1999 for 12,299 female and 43,307 male hourly and salaried petrochemical workers using company physical examination data.

RESULTS

Nearly half of hourly male and female employees smoked during the study period, compared with 38% of salaried males and 29% of females. Smoking prevalence in the 1950s reached 80% and 66% among female and male hourly workers, respectively, significantly higher than the US general population.

CONCLUSIONS

As hourly workers typically comprise higher exposure groups and expected case counts are typically generated from the US general population, biased risk estimates may result from standardized mortality ratio analyses if smoking rate differences are not accounted for.

Correlation between preconception maternal non-occupational exposure to interior decoration or oil paint odour and average birth weight of neonates: findings from a nationwide cohort study in China's rural areas

BACKGROUND

Birth weight is a critical indicator of neonatal health and foretells people's health in adolescence and even adulthood. Some researchers have warned against the adverse effects on babies' birth weight of exposure to pollutants in interior decoration or oil paint by odour intake. This study evaluated the effects of maternal exposure to such factors before conception on the birth weights of neonates.

METHODS

Data on 213 461 cases in this study were from the database of the free National Pre-pregnancy Checkups Project. Defined as 'exposed' were those women exposed to oil paint odour or interior decoration at home or in the workplace within 6 months before their pregnancy. The study focused on revealing the correlation between such exposure and the birth weight of the neonates of these women, especially the incidence of macrosomia and low birth weight (LBW). Statistical analysis was conducted using the Kruskal-Wallis H test, the Mann-Whitney U test and logistic regression.

RESULTS

The birth weight of babies from mothers non-occupationally exposed to such settings averaged 3465 g (range 3150-3650 g), whereas the birth weight of those from mothers free of such exposure averaged 3300 g (range 3000-3600g). Maternal exposure preconception to interior decoration or oil paint odour reduced the incidence of LBW in their babies (p=0.003, OR 0.749, 95% CI 0.617 to 0.909). Such exposure may also augment the probability of macrosomia (p<0.001, OR 1.297, 95% CI 1.133 to 1.484).

CONCLUSION

Maternal exposure to interior decoration or oil paint odour preconception may increase the average birth weight of neonates, as well as the incidence of macrosomia.