Case‐control study of congenital defects and parental employment in health care

Abstract

Health care workers may be occupationally exposed to known and suspected teratogens including viruses, anesthetic gases, sterilants, mercury, and x-radiation. To assess the risk of congenital defects among offspring of health care workers, we analyzed parental occupational histories for 4,915 case babies with congenital defects, registered during the years 1968-1980 by the Metropolitan Atlanta Congenital Defects Program (MACDP) registry, and for 3,027 control babies born without defects during the same period. Offspring of mothers employed in a nursing occupation during the periconceptional period had a modest excess risk of having at least one congenital defect (relative risk [RR] = 1.42; 95% confidence interval [CI] 1.06-1.88); the offspring were at statistically significant increased risk of having anencephaly or spina bifida (RR = 2.00; 95% CI 1.01-4.30), coarctation of the aorta (RR = 2.06; 95% CI 1.10-3.82), genital system defects (RR = 1.61; 95% CI 1.03-2.53), and urinary system defects (RR = 3.43; 95% CI 1.41-8.34). These associations were not confounded by maternal age, education, or alcohol consumption. Offspring of mothers employed in administrative or clerical jobs in the health care industry also had a modest excess risk of defects (RR = 1.35; 95% CI 0.96-1.90), including a statistically significant excess risk of limb defects. We also found associations between neural tube defects and potential exposure to anesthetic gases and to x-radiation, but each association was based on only three case babies of potentially exposed parents. We found no associations between defects and paternal health care employment, except for a few individual defects, and these were based on small numbers of exposed subjects. Only one of five previous studies reviewed found an increased risk of congenital defects among offspring of nurses, but three of the four negative studies had substantially smaller sample sizes than the present study. Detection bias may be a possible explanation for the apparent excess risk of certain defects among offspring of nurses.

Occupational Exposures and Adverse Pregnancy Outcomes Among Nurses: A Systematic Review and Meta-Analysis

“…The definition of shift work also varied, with a vague definition provided in one study. 46 Most studies included in the present systematic review primarily focused on assessing exposure occurring any time during pregnancy 3,12,13,[35][36][37][38][39]42,44,47 or exposure in the first trimester. 2,3,5,41,43,46 Exposure during the last menstrual period 41 or around the period of conception 11 was also reported, but some studies failed to identify a specific time window of susceptibility.…”

“…The eligible studies were conducted in the United States, 9,12,40,[43][44][45]47 Finland, 33,46 Sweden, 2,3,34,37,40 Canada, 36 Denmark, 10,38 France, 5,42 Belgium, 39 the Netherlands, 13 and the Czech Republic 14 ( Table 1). The most relevant characteristics of the eligible studies are shown in Table 1.…”

“…With regard to anesthetic gases, different populations at risk were studied, including operating room workers (excluding physicians), 4,9,11,12,35,36,38,39,[45][46][47] midwives, 3 and dental assistants. 36,37,41,44 These population groups are not expected to have similar levels of exposure to anesthetic gases, and the risk of adverse pregnancy outcomes may differ.…”

Inter‐rater agreement of assessed prenatal maternal occupational exposures to lead

“…For example, a number of epidemiologic studies have identified possible associations of parental occupational exposures with birth defects (Cordier et al, 1997;Correa-Villaseñ or et al, 1991Garcia et al, 1998;Khattak et al, 1999;Matte et al, 1993;McMartin et al, 1998;Olshan et al, 1991;Schnitzer et al, 1995;Shaw et al, 1999a,b;Tikkanen and Heinonen, 1992). However, because assessment of parental occupational exposures in these studies was based either on reported industry and job title, which lack information on specific exposures, or on self-reports of exposures to specific agents, which suffer from low sensitivity and potential recall bias (Garcia, 1998;Bauer et al, 1999), it is likely that the exposure groups evaluated included some misclassified subjects and that the observed odds ratios were biased and imprecise.…”

Spina bifida and parental occupation in a Swedish register-based study

“…Most studies include congenital anomalies in general or defects of the central nervous system (CNS) as a group, including neural tube defects. In these studies, some associations have been found for women working in industry, construction, transport and communication (5,6), dental surgeries (7), and nursing (8) and for women exposed to organic solvents (9). Studies on fathers yielded increased risks for painters (lo), agricultural workers (1 I), workers in the food, beverage, wood and textile industries (12), and fathers exposed to low-level radiation (1 3).…”