Parental exposures and occurence of adverse pregnancy outcomes and childhood atopic diseases

Abstract

The aim of this thesis was to investigate whether parental laboratory work is associated with adverse pregnancy outcomes, and if maternal occupation as well as exposure to organic solvents and smoking during pregnancy are associated with atopic diseases in childhood.

The studies were based on two different study populations. (1) A Swedish source cohort of female and male biomedical laboratory and non-laboratory university employees, 1970-1989. In order to identify pregnancies, outcomes, and additional data, the males were linked to the multi-generation register and their partners, as well as all female employees, to the Swedish Medical Birth Register. Exposure data was based on employee records and questionnaires, sent to research group leaders, concerning the use of agents and techniques. The final study populations consisted of 3003 female pregnancies and 4190 male pregnancies. (2) A Danish cohort encompassing pregnant mothers from Odense and Aalborg 1984-1987. Information on smoking and occupational job titles was collected during pregnancy, and an assessment of organic solvent exposure was performed by occupational specialists. The children were later followed up by questionnaires to parents, at age 14-18, to retrieve information about health parameters such as atopic diseases during childhood. This resulted in a final study population of 7844 children.

Logistic regression analyses did not show any significant associations between female or male laboratory work in general and adverse pregnancy outcomes. However, when analyses were based on specific agents/techniques, maternal organic solvent exposure "periconceptionally" gave an increased odds ratio (OR) of 2.5 and 95% confidence interval (CI) of 1.0-6.0 for major malformations. Maternal work with benzene resulted in increased risk estimates for major malformations, especially neural crest malformations (OR 5.3, Cl 1.4-2 1. 1). An increased OR for neural crest malformations was found for paternal work with carcinogens. Paternal work with radioactive isotopes also showed a slightly increased ratio for high birth weight (OR 1.8, CI 1.0-3.2) and altered male/female sex ratio (relative risk 1.2, CI 1.0-1.4). Maternal smoking in pregnancy was associated with wheezing (OR 1.2, Cl 1.1-1.5), in a dose response pattern. No association was seen with asthma. Shift work was marginally associated with asthma (OR 1.2, CI 1.0-1.5), and there was a tendency towards an increased risk for asthma and hay fever in association with high solvent exposure, with ORs of 2.0 (CI 0.7-6. 1) and 2.6 (CI 1.0-6.9), respectively. Moreover, in an explorative analysis we found elevated risk estimates for a number of occupational groups; e.g. "bakers, pastry cooks, and confectionary makers", dental assistants, "electrical and electronic assemblers", "sewers and embroiders", and "bookbinders and related workers".

In conclusion, the results do not suggest an association between parental biomedical laboratory work in general and pregnancy outcomes. However, specific exposures could be of concern for both female and male employees, most notably maternal organic solvent use. The results on maternal smoking in pregnancy supported an association with wheezing. Certain female occupations in pregnancy might also be associated with childhood atopic diseases, and one potential risk factor could be organic solvent exposure.