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 occupation as a nail technician or hairdresser during pregnancy and birth defects, National Birth Defects Prevention Study, 1997-2011.

OBJECTIVE: Nail technicians and hairdressers may be exposed to chemicals with potential reproductive effects. While studies have examined birth defects in children of hairdressers, those in children of nail technicians have not been evaluated. We investigated associations between selected birth defects and maternal occupation as a nail technician or hairdresser versus a non-cosmetology occupation during pregnancy. METHODS: We analysed population-based case-control data from the multisite National Birth Defects Prevention Study, 1997-2011. Cases were fetuses or infants with major structural birth defects; controls were live-born infants without major birth defects. Expert raters classified self-reported maternal jobs as nail technician, combination nail technician-hairdresser, hairdresser, other cosmetology work or non-cosmetology work. We used logistic regression to calculate adjusted ORs and 95% CIs for associations between occupation during pregnancy and birth defects, controlling for age, smoking, education and race/ethnicity. RESULTS: Sixty-one mothers worked as nail technicians, 196 as hairdressers, 39 as combination nail technician-hairdressers and 42 810 as non-cosmetologists. The strongest associations among nail technicians included seven congenital heart defect (CHD) groups (ORs ranging from 2.7 to 3.5) and neural tube defects (OR=2.6, CI=0.8 to 8.4). Birth defects most strongly associated with hairdressing included anotia/microtia (OR=2.1, CI=0.6 to 6.9) and cleft lip with cleft palate (OR=2.0, CI=1.1 to 3.7). All oral cleft groups were associated with combination nail technician-hairdresser work (ORs ranging from 4.2 to 5.3). CONCLUSIONS: Small samples resulted in wide CIs. Still, results suggest associations between maternal nail technician work during pregnancy and CHDs and between hairdressing work and oral clefts.

Characteristics of Women with Urinary Tract Infection in Pregnancy.

Background: Urinary tract infection (UTI) is the most common bacterial infection in pregnancy. Known risk factors for UTI in pregnancy include diabetes and certain urologic conditions. Other maternal characteristics might also be associated with risk and could provide clues to the etiology of UTI in pregnancy. Our objective was to identify maternal characteristics associated with UTI in pregnancy. Materials and Methods: We used data from pregnant women participating in the National Birth Defects Prevention Study, a population-based study of risk factors for major structural birth defects in 10 U.S. sites, from 1997 to 2011. In cross-sectional analyses, we used multivariable log-binomial regression to estimate prevalence ratios (PRs) and 95% confidence intervals (CIs) for associations between self-reported maternal characteristics and UTI in pregnancy. Results: In our sample of 41,869 women, the overall prevalence of reported UTI in pregnancy was 18%, but ranged from 11% to 26% between study sites. In adjusted models, diabetes was moderately associated with higher UTI prevalence (PR 1.39, 95% CI: 1.24-1.57). Higher UTI prevalence was associated even more strongly with low educational attainment (PR 2.06, 95% CI: 1.77-2.40 for some high school vs. graduate school), low household income (PR 1.64, 95% CI: 1.46-1.84 for <$10,000 vs. ≥$50,000), and race/ethnicity (PR 1.45, 95% CI: 1.13-1.80 for American Indian or Alaska Native vs. White women). Conclusions: About one in six women reported UTI in pregnancy but the prevalence varied markedly by geography and maternal characteristics. This variability could provide clues to the causes of UTI in pregnancy.

Testing and Validating Semi-automated Approaches to the Occupational Exposure Assessment of Polycyclic Aromatic Hydrocarbons.

INTRODUCTION: When it is not possible to capture direct measures of occupational exposure or conduct biomonitoring, retrospective exposure assessment methods are often used. Among the common retrospective assessment methods, assigning exposure estimates by multiple expert rater review of detailed job descriptions is typically the most valid, but also the most time-consuming and expensive. Development of screening protocols to prioritize a subset of jobs for expert rater review can reduce the exposure assessment cost and time requirement, but there is often little data with which to evaluate different screening approaches. We used existing job-by-job exposure assessment data (assigned by consensus between multiple expert raters) from a large, population-based study of women to create and test screening algorithms for polycyclic aromatic hydrocarbons (PAHs) that would be suitable for use in other population-based studies. METHODS: We evaluated three approaches to creating a screening algorithm: a machine-learning algorithm, a set of a priori decision rules created by experts based on features (such as keywords) found in the job description, and a hybrid algorithm incorporating both sets of criteria. All coded jobs held by mothers of infants participating in National Birth Defects Prevention Study (NBDPS) (n = 35,424) were used in developing or testing the screening algorithms. The job narrative fields considered for all approaches included job title, type of product made by the company, main activities or duties, and chemicals or substances handled. Each screening approach was evaluated against the consensus rating of two or more expert raters. RESULTS: The machine-learning algorithm considered over 30,000 keywords and industry/occupation codes (separate and in combination). Overall, the hybrid method had a similar sensitivity (87.1%) as the expert decision rules (85.5%) but was higher than the machine-learning algorithm (67.7%). Specificity was best in the machine-learning algorithm (98.1%), compared to the expert decision rules (89.2%) and hybrid approach (89.1%). Using different probability cutoffs in the hybrid approach resulted in improvements in sensitivity (24-30%), without the loss of much specificity (7-18%). CONCLUSION: Both expert decision rules and the machine-learning algorithm performed reasonably well in identifying the majority of jobs with potential exposure to PAHs. The hybrid screening approach demonstrated that by reviewing approximately 20% of the total jobs, it could identify 87% of all jobs exposed to PAHs; sensitivity could be further increased, albeit with a decrease in specificity, by adjusting the algorithm. The resulting screening algorithm could be applied to other population-based studies of women. The process of developing the algorithm also provides a useful illustration of the strengths and potential pitfalls of these approaches to developing exposure assessment algorithms.

Prepregnancy handling of antineoplastic drugs and risk of miscarriage in female nurses.

PURPOSE: To examine the association betweenantineoplastic drug (AD) handling and risk of miscarriage. METHODS: Nurses' Health Study-3 participants self-reported AD administration and engineering controls (ECs) and personal protective equipment (PPE) use at baseline. We estimated the hazard ratio (HR) of miscarriage in relation to baseline AD handling using multivariable Cox proportional regression. RESULTS: Overall, 2440 nurses reported 3327 pregnancies, with 550 (17%) ended in miscarriages. Twelve percent of nurses self-reported currently handling AD and 28% previously handling AD. Compared with nurses who never handled AD, nurses who handled AD at baseline had an adjusted HR of miscarriage of 1.26 (95% confidence interval [CI], 0.97-1.64). This association was stronger after 12-weeks gestation (HR=2.39 [95% CI, 1.13-5.07]). Nurses who did not always use gloves had HR of 1.51 (95% CI, 0.91-2.51) compared with 1.19 (95% CI, 0.89-1.60) for those always using gloves; nurses who did not always use gowns had HR of 1.32 (95% CI, 0.95-1.83) compared with 1.19 (95% CI, 0.81-1.75) for nurses always using gowns. CONCLUSIONS: We observed a suggestive association between AD handling and miscarriage, particularly among nurses who did not consistently use PPE and EC with stronger associations for second trimester losses.

Maternal occupational exposure to polycyclic aromatic hydrocarbons and the risk of isolated congenital heart defects among offspring.

BACKGROUND: Although there is evidence in experimental model systems that exposure to polycyclic aromatic hydrocarbons (PAHs) is linked with congenital heart defects (CHDs), few studies have examined the association in humans. We conducted a case-control study to examine the association between maternal exposure to PAHs and CHDs in offspring using data from the National Birth Defects Prevention Study (NBDPS) (1997-2011). METHODS: We obtained detailed information on maternal occupation during the month before to three months after conception. Expert raters, masked to case-control status, assessed job descriptions to assign categorical levels of exposure. Categories were quantitatively mapped to estimate cumulative exposure to PAHs, incorporating exposure intensity, frequency, work duration, and work hours. Quartiles were generated for cumulative maternal exposure to PAHs. Crude and adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were estimated using unconditional logistic regression for quartiles of PAH exposure and six CHD groupings (e.g. conotruncal) and specific subtypes (e.g. tetralogy of Fallot [ToF]). Final models were adjusted for maternal age, race/ethnicity, education, smoking, anticonvulsant use, folic acid supplementation, and study center. RESULTS: There were 4,775 case and 7,734 control infants eligible for the study. The prevalence of occupational exposure to PAHs was 10.2% among both case and control mothers. In adjusted analysis, compared to mothers with no occupational PAH exposure, those in the highest quartile of exposure were more likely to have offspring in the conotruncal heart defects group (OR 1.41; 95% CI 1.00-2.00), and with ToF (OR 1.83; 95% CI 1.21-2.78). CONCLUSIONS: Women in the highest quartile of estimated cumulative occupational PAH exposure during early pregnancy were more likely to have offspring with conotruncal heart defects, specifically ToF, compared to women with no occupational PAH exposure. Other comparisons between PAHs and other CHDs subgroups did not show any statistically precise associations.

Association between maternal occupational exposure to polycyclic aromatic hydrocarbons and rare birth defects of the face and central nervous system.

BACKGROUND: Previous studies suggested associations between maternal smoking, a source of exposure to polycyclic aromatic hydrocarbons (PAHs) and other chemicals, and central nervous system and face birth defects; however, no previous studies have evaluated maternal occupational PAH exposure itself. METHODS: Jobs held in the periconceptional period were retrospectively assigned for occupational PAH exposures. Associations between maternal occupational PAH exposure and selected rare defects of the face (cataracts, microphthalmia, glaucoma, microtia, and choanal atresia) and central nervous system (holoprosencephaly, hydrocephaly, cerebellar hypoplasia, and Dandy-Walker malformation) were evaluated using data from the National Birth Defects Prevention Study, a population-based case-control study in the United States. Crude and adjusted odds ratios (ORs) with 95% confidence intervals were calculated to estimate associations between each evaluated defect and PAH exposure using multivariable logistic regression. RESULTS: Food and beverage serving, as well as cooks and food preparation occupations, were among the most frequent jobs held by exposed mothers. Cataracts, microtia, microphthalmia, and holoprosencephaly were significantly associated with PAH exposure with evidence of dose-response (P-values for trend ≤.05). Hydrocephaly was associated with any PAH exposure, but not significant for trend. Sensitivity analyses that reduced possible sources of exposure misclassification tended to strengthen associations. CONCLUSIONS: This is the first population-based case-control study to evaluate associations between maternal occupational PAH exposures and these rare birth defects of the central nervous system and face.

Maternal Occupational Oil Mist Exposure and Birth Defects, National Birth Defects Prevention Study, 1997⁻2011.

Workers in various industries can be exposed to oil mists when oil-based fluids are aerosolized during work processes. Oil mists can be inhaled or deposited on the skin. Little research exists on the reproductive effects of oil mist exposure in pregnant workers. We aimed to investigate associations between occupational oil mist exposure in early pregnancy and a spectrum of birth defects using data from 22,011 case mothers and 8140 control mothers in the National Birth Defects Prevention Study. In total, 150 mothers were rated as exposed. Manufacturing jobs, particularly apparel manufacturing, comprised the largest groups of exposed mothers. Mothers of infants with septal heart defects (odds ratio (OR): 1.8, 95% confidence interval (CI): 1.0-3.3), and especially perimembranous ventricular septal defects (OR: 2.5, CI: 1.2-5.2), were more likely to be occupationally exposed to oil mists in early pregnancy than control mothers; and their rater-estimated cumulative exposure was more likely to be higher. This was the first U.S. study evaluating associations between oil mist exposure and a broad spectrum of birth defects. Our results are consistent with previous European studies, supporting a potential association between oil-based exposures and congenital heart defects. Further research is needed to evaluate the reproductive effects of occupational oil mist exposure.

CE: Original Research: Antineoplastic Drug Administration by Pregnant and Nonpregnant Nurses: An Exploration of the Use of Protective Gloves and Gowns.

: Background: Many antineoplastic (chemotherapeutic) drugs are known or probable human carcinogens, and many have been shown to be reproductive toxicants in cancer patients. Evidence from occupational exposure studies suggests that health care workers who have long-term, low-level occupational exposure to antineoplastic drugs have an increased risk of adverse reproductive outcomes. It's recommended that, at minimum, nurses who handle or administer such drugs should wear double gloves and a nonabsorbent gown to protect themselves. But it's unclear to what extent nurses do. PURPOSE: This study assessed glove and gown use by female pregnant and nonpregnant nurses who administer antineoplastic drugs in the United States and Canada. METHODS: We used data collected from more than 40,000 nurses participating in the Nurses' Health Study 3. The use of gloves and gowns and administration of antineoplastic drugs within the past month (among nonpregnant nurses) or within the first 20 weeks of pregnancy (among pregnant nurses) were self-reported via questionnaire. RESULTS: Administration of antineoplastic drugs at any time during their career was reported by 36% of nonpregnant nurses, including 27% who reported administering these drugs within the past month. Seven percent of pregnant nurses reported administering antineoplastic drugs during the first 20 weeks of pregnancy. Twelve percent of nonpregnant nurses and 9% of pregnant nurses indicated that they never wore gloves when administering antineoplastic drugs, and 42% of nonpregnant nurses and 38% of pregnant nurses reported never using a gown. The percentage of nonpregnant nurses who reported not wearing gloves varied by type of administration: 32% of those who administered antineoplastic drugs only as crushed pills never wore gloves, compared with 5% of those who administered such drugs only via infusion. CONCLUSION: Despite longstanding recommendations for the safe handling of antineoplastic and other hazardous drugs, many nurses-including those who are pregnant-reported not wearing protective gloves and gowns, which are considered the minimum protective equipment when administering such drugs. These findings underscore the need for further education and training to ensure that both employers and nurses understand the risks involved and know which precautionary measures will minimize such exposures.

Maternal occupational cadmium exposure and nonsyndromic orofacial clefts.

BACKGROUND: Cigarette smoking is a well-studied risk factor for orofacial clefts (OFCs). Little is known about which constituents in cigarette smoke contribute to this teratogenicity in humans. One constituent, cadmium, has been associated with OFCs in animal studies; in humans, the role of maternal cadmium exposure on OFCs, independent of cigarette smoke, is unclear. In particular, the relation between maternal occupational cadmium exposure and OFCs is largely unexplored. METHODS: Using data from a large, population-based case-control study, we compared expert rater assessed maternal occupational cadmium exposure from self-reported occupational histories during the period 1 month before through 3 months after conception between OFC cases (n = 1,185) and unaffected controls (n = 2,832). Multivariable logistic regression analyses were used to estimate adjusted odds ratios (aORs) and 95% confidence intervals for any (yes/no) and cumulative (no, low, high exposure) occupational cadmium exposures and all OFCs, cleft lip ± cleft palate (CL/P) and cleft palate (CP). RESULTS: Overall, 45 mothers (cases = 13, controls = 32) were rated as having occupational cadmium exposure. Comparing all OFCs to controls, we observed inverse, nonsignificant aORs for any or low exposure, and positive, nonsignificant aORs for high exposure. Where data were available, aORs for CL/P and CP tended to parallel those for all OFCs. CONCLUSION: To our knowledge, this is the first study to specifically examine maternal occupational cadmium exposure and OFCs, using expert rater exposure assessment. The small numbers of exposed mothers observed, however, led to imprecise estimates. Continued research using more detailed occupational exposure assessment and increased sample sizes is recommended.

Agreement between two methods for retrospective assessment of occupational exposure intensity to six chlorinated solvents: Data from The National Birth Defects Prevention Study.

The wide variety of jobs encountered in population-based studies makes retrospective exposure assessment challenging in occupational epidemiology. In this analysis, two methods for estimating exposure intensity to chlorinated solvents are compared: rated (assigned by an expert rater) and modeled (assigned using statistical models). Estimates of rated and modeled intensities were compared for jobs held by mothers participating in the National Birth Defects Prevention Study with possible exposure to six chlorinated solvents: carbon tetrachloride, chloroform, methylene chloride, perchloroethylene, 1,1,1-trichloroethane, and trichloroethylene. For each possibly exposed job, an industrial hygienist assigned (1) an exposure intensity (rated intensity) and (2) determinants of exposure to be used in a statistical model of exposure intensity (modeled intensity). Of 12,326 reported jobs, between 31 (0.3%) and 746 (6%) jobs were rated as possibly exposed to each of the six solvents. Agreement between rated and modeled intensities was low overall (Spearman correlation coefficient range: -0.09 to 0.28; kappa range: -0.23 to 0.43). Although no air measurements were available to determine if rated or modeled estimates were more accurate, review of participants' job titles showed that modeled estimates were often unexpectedly high given the low-exposure tasks found in these jobs. Differences between the high-exposure jobs used to create the statistical models (obtained from air measurements in the published literature) and the low-exposure jobs in the actual study population is a potential explanation for the disagreement between the two methods. Investigators should be aware that statistical models estimating exposure intensity using existing data from one type of worker population might not be generalizable to all populations of workers.

Factors associated with employment status before and during pregnancy: Implications for studies of pregnancy outcomes.

BACKGROUND: Potential confounding or effect modification by employment status is frequently overlooked in pregnancy outcome studies. METHODS: To characterize how employed and non-employed women differ, we compared demographics, behaviors, and reproductive histories by maternal employment status for 8,343 mothers of control (non-malformed) infants in the National Birth Defects Prevention Study (1997-2007) and developed a multivariable model for employment status anytime during pregnancy and the 3 months before conception. RESULTS: Sixteen factors were independently associated with employment before or during pregnancy, including: maternal age, pre-pregnancy body mass index, pregnancy intention, periconceptional/first trimester smoking and alcohol consumption, and household income. CONCLUSIONS: Employment status was significantly associated with many common risk factors for adverse pregnancy outcomes. Pregnancy outcome studies should consider adjustment or stratification by employment status. In studies of occupational exposures, these differences may cause uncontrollable confounding if non-employed women are treated as unexposed instead of excluded from analysis. Am. J. Ind. Med. 60:329-341, 2017. © 2017 Wiley Periodicals, Inc.

Paternal and joint parental occupational pesticide exposure and spina bifida in the National Birth Defects Prevention Study, 1997 to 2002.

BACKGROUND: Because of persistent concerns over the association between pesticides and spina bifida, we examined the role of paternal and combined parental occupational pesticide exposures in spina bifida in offspring using data from a large population-based study of birth defects. METHODS: Occupational information from fathers of 291 spina bifida cases and 2745 unaffected live born control infants with estimated dates of delivery from 1997 to 2002 were collected by means of maternal report. Two expert industrial hygienists estimated exposure intensity and frequency to insecticides, herbicides, and fungicides. Multivariable logistic regression models were used to estimate adjusted odds ratios (aOR) and 95% confidence intervals (CI) for exposure to any pesticide and to any class of pesticide (yes/no; and by median), and exposure to combinations of pesticides (yes/no) and risk of spina bifida. Adjusted odds ratios were also estimated by parent exposed to pesticides (neither, mother only, father only, both parents). RESULTS: Joint parental occupational pesticide exposure was positively associated with spina bifida (aOR, 1.5; 95% CI, 0.9-2.4) when compared with infants with neither maternal nor paternal exposures; a similar association was not observed when only one parent was exposed. There was a suggested positive association between combined paternal insecticide and fungicide exposures and spina bifida (aOR, 1.5; 95% CI, 0.8-2.8), however, nearly all other aORs were close to unity. CONCLUSION: Overall, there was little evidence paternal occupational pesticide exposure was associated with spina bifida. However, the small numbers make it difficult to precisely evaluate the role of pesticide classes, individually and in combination. Birth Defects Research (Part A) 106:963-971, 2016. © 2016 Wiley Periodicals, Inc.

"Will my work affect my pregnancy?" Resources for anticipating and answering patients' questions.

BACKGROUND: Authoritative information on occupational reproductive hazards is scarce and complex because exposure levels vary, multiple exposures may be present, and the reproductive toxicity of many agents remains unknown. For these reasons, women's health providers may find it challenging to effectively address workplace reproductive health issues with their patients who are pregnant, breast-feeding, or considering pregnancy. Reproductive epidemiologists at the Centers for Disease Control and Prevention National Institute for Occupational Safety and Health answered >200 public requests for occupational reproductive health information during 2009 through 2013. The most frequent occupations represented were health care (41%) and laboratory work (18%). The most common requests for exposure information concerned solvents (14%), anesthetic gases (10%), formaldehyde (7%), infectious agents in laboratories (7%) or health care settings (7%), and physical agents (14%), including ionizing radiation (6%). Information for developing workplace policies or guidelines was sought by 12% of the requestors. Occupational exposure effects on breast-feeding were an increasing concern among working women. Based on information developed in response to these requestors, information is provided for discussing workplace exposures with patients, assessing potential workplace reproductive hazards, and helping patients determine the best options for safe work in pregnancy. Appendices provide resources to address specific occupational exposures, employee groups, personal protective equipment, breast-feeding, and workplace regulations regarding work and pregnancy. These tools can help identify those most at risk of occupational reproductive hazards and improve workers' reproductive health. The information can also be used to inform research priorities and assist the development of workplace reproductive health policies.

Maternal occupational exposure to polycyclic aromatic hydrocarbons and craniosynostosis among offspring in the National Birth Defects Prevention Study.

BACKGROUND: Evidence in animal models and humans suggests that exposure to polycyclic aromatic hydrocarbons (PAHs) may lead to birth defects. To our knowledge, this relationship has not been evaluated for craniosynostosis, a birth defect characterized by the premature closure of sutures in the skull. We conducted a case-control study to examine associations between maternal occupational exposure to PAHs and craniosynostosis. METHODS: We used data from craniosynostosis cases and control infants in the National Birth Defects Prevention Study (NBDPS) with estimated delivery dates from 1997 to 2002. Industrial hygienists reviewed occupational data from the computer-assisted telephone interview and assigned a yes/no rating of probable occupational PAH exposure for each job from 1 month before conception through delivery. We used logistic regression to assess the association between occupational exposure to PAHs and craniosynostosis. RESULTS: The prevalence of exposure was 5.3% in case mothers (16/300) and 3.7% in control mothers (107/2,886). We observed a positive association between exposure to PAHs during the 1 month before conception through the third month of pregnancy and craniosynostosis (odds ratio [OR] = 1.75; 95% confidence interval [CI], 1.01-3.05) after adjusting for maternal age and maternal education. The number of cases for each craniosynostosis subtype limited subtype analyses to sagittal craniosynostosis; the odds ratio remained similar (OR = 1.76, 95% CI, 0.82-3.75), but was not significant. CONCLUSION: Our findings support a moderate association between maternal occupational exposure to PAHs and craniosynostosis. Additional work is needed to better characterize susceptibility and the role PAHs may play on specific craniosynostosis subtypes.

Maternal occupational pesticide exposure and risk of congenital heart defects in the National Birth Defects Prevention Study.

BACKGROUND: Congenital heart defects (CHDs) are common birth defects, affecting approximately 1% of live births. Pesticide exposure has been suggested as an etiologic factor for CHDs, but previous results were inconsistent. METHODS: We examined maternal occupational exposure to fungicides, insecticides, and herbicides for 3328 infants with CHDs and 2988 unaffected control infants of employed mothers using data for 1997 through 2002 births from the National Birth Defects Prevention Study, a population-based multisite case-control study. Potential pesticide exposure from 1 month before conception through the first trimester of pregnancy was assigned by an expert-guided task-exposure matrix and job history details self-reported by mothers. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariable logistic regression. RESULTS: Maternal occupational exposure to pesticides was not associated with CHDs overall. In examining specific CHD subtypes compared with controls, some novel associations were observed with higher estimated pesticide exposure: insecticides only and secundum atrial septal defect (OR = 1.8; 95% CI, 1.3-2.7, 40 exposed cases); both insecticides and herbicides and hypoplastic left heart syndrome (OR = 5.1; 95% CI, 1.7-15.3, 4 exposed cases), as well as pulmonary valve stenosis (OR = 3.6; 95% CI, 1.3-10.1, 5 exposed cases); and insecticides, herbicides, and fungicides and tetralogy of Fallot (TOF) (OR = 2.2; 95% CI, 1.2-4.0, 13 exposed cases). CONCLUSION: Broad pesticide exposure categories were not associated with CHDs overall, but examining specific CHD subtypes revealed some increased odds ratios. These results highlight the importance of examining specific CHDs separately. Because of multiple comparisons, additional work is needed to verify these associations.

Maternal periconceptional occupational pesticide exposure and neural tube defects.

BACKGROUND: Adverse associations between maternal pesticide exposure and neural tube defects (NTDs) have been suggested but not consistently observed. This study used data from the multisite National Birth Defects Prevention Study to examine associations between maternal periconceptional (1 month preconception through 2 months postconception) occupational pesticide exposure and NTDs. METHODS: Mothers of 502 NTD cases and 2950 unaffected live-born control infants with estimated delivery dates from 1997 through 2002 were included. Duration, categorical intensity scores, and categorical frequency scores for pesticide classes (e.g., insecticides) were assigned using a modified, literature-based job-exposure matrix and maternal-reported occupational histories. Adjusted odds ratios (aORs) and 95% confidence intervals were estimated based on fitted multivariable logistic regression models that described associations between maternal periconceptional occupational pesticide exposure and NTDs. The aORs were estimated for pesticide exposure (any [yes/no] and cumulative exposure [intensity × frequency × duration] to any pesticide class, each pesticide class, or combination of pesticide classes) and all NTD cases combined and NTD subtypes. RESULTS: Positive, but marginally significant or nonsignificant, aORs were observed for exposure to insecticides + herbicides for all NTD cases combined and for spina bifida alone. Similarly, positive aORs were observed for any exposure and cumulative exposure to insecticides + herbicides + fungicides and anencephaly alone and encephalocele alone. All other aORs were near unity. CONCLUSION: Pesticide exposure associations varied by NTD subtype and pesticide class. Several aORs were increased, but not significantly. Future work should continue to examine associations between pesticide classes and NTD subtypes using a detailed occupational pesticide exposure assessment and examine pesticide exposures outside the workplace.

Maternal occupational exposure to polycyclic aromatic hydrocarbons and small for gestational age offspring.

OBJECTIVES: While some of the highest maternal exposures to polycyclic aromatic hydrocarbons (PAHs) occur in the workplace, there is only one previous study of occupational PAH exposure and adverse pregnancy outcomes. We sought to extend this literature using interview data combined with detailed exposure assessment. METHODS: Data for 1997-2002 were analysed from mothers of infants without major birth defects in the National Birth Defects Prevention Study, a large population-based case-control study in the USA. Maternal telephone interviews yielded information on jobs held in the month before conception through delivery. From 6252 eligible control mothers, 2803 completed the interview, had a job, met other selection criteria, and were included in the analysis. Two industrial hygienists independently assessed occupational exposure to PAHs from the interview and reviewed results with a third to reach consensus. Small for gestational age (SGA) was the only adverse pregnancy outcome with enough exposed cases to yield meaningful results. Logistic regression estimated crude and adjusted ORs. RESULTS: Of the 2803 mothers, 221 (7.9%) had infants who were SGA. Occupational PAH exposure was found for 17 (7.7%) of the mothers with SGA offspring and 102 (4.0%) of the remaining mothers. Almost half the jobs with exposure were related to food preparation and serving. After adjustment for maternal age, there was a significant association of occupational exposure with SGA (OR=2.2, 95% CI 1.3 to 3.8). CONCLUSIONS: Maternal occupational exposure to PAHs was found to be associated with increased risk of SGA offspring.

Maternal periconceptional occupational exposure to pesticides and selected musculoskeletal birth defects.

This population-based U.S. study investigated the association between major musculoskeletal malformations and periconceptional maternal occupational pesticide exposure for a wide range of occupations. We conducted a multi-site case-control analysis using data from the National Birth Defects Prevention Study among employed women with due dates from October 1, 1997 through December 31, 2002. Cases included 871 live-born, stillborn, or electively terminated fetuses with isolated craniosynostosis, gastroschisis, diaphragmatic hernia, or transverse limb deficiencies. Controls included 2857 live-born infants without major malformations. Using self-reported maternal occupational information, an industrial hygienist used a job-exposure matrix and expert opinion to evaluate the potential for exposure to insecticides, herbicides or fungicides for each job held during one month pre-conception through three months post-conception. Exposures analyzed included any exposure (yes/no) to pesticides, to insecticides only, to both insecticides and herbicides (I+H) and to insecticides, herbicides and fungicides (I+H+F). We used logistic regression to evaluate the association between exposures and defects, controlling for infant and maternal risk factors. Occupational exposure to I+H+F was associated with gastroschisis among infants of women aged 20 years or older (adjusted odds ratio [aOR]=1.88; 95% confidence interval [CI]: 1.16-3.05), but not for women under age 20 (aOR=0.48; 95% CI: 0.20-1.16). We found no significant associations for the other defects. Additional research is needed to validate these findings in a separate population.

Differences in folic acid use, prenatal care, smoking, and drinking in early pregnancy by occupation.

OBJECTIVE: To describe differences in four high risk periconceptional behaviors (lack of folic acid supplementation, lack of early prenatal care, smoking, and drinking) by maternal occupation. METHODS: Analyses were conducted among women in the National Birth Defects Prevention Study who delivered liveborn infants without birth defects. Periconceptional occupational data were collected using a computer-assisted telephone interview and occupational coding was performed using the 2000 Standard Occupational Classification System. Logistic regression analyses were conducted to determine whether prevalence of behaviors differed between occupational groups. RESULTS: Subjects included 5153 women employed during early pregnancy from 1997 to 2007. Compared to women in management, business, science, and arts occupations, women in other occupations (e.g., service occupations) were significantly more likely to engage in all four high risk behaviors. Specifically, women in food preparation/serving-related occupations were significantly more likely to engage in all four behaviors compared to women in all other occupational groups (odds ratios: 1.8-3.0), while women in education/training/library occupations were significantly less likely to do so (odds ratios: 0.2-0.5). CONCLUSION: We identified several occupational groups with an increased prevalence of high-risk maternal behaviors during pregnancy. Our findings could aid in developing interventions targeted towards women in these occupational groups.