Effects of maternal work activity during pregnancy on infant malformations.

This article examines the association between two birth defects, neural tube defects and oral cleft defects, and maternal physical work demands during the periconceptional period. A case-control study was conducted by comparing exposure characteristics of mothers of malformed infants, as ascertained from the New York State Congenital Malformations Registry (n = 520), with mothers of non-malformed infants (n = 1154). Case groups were further subdivided on whether infants had additional defects. Occupational exposure information was collected from a self-administered questionnaire, and demographic variables from vital records. The results showed no general differences between cases and controls in most variables. However, those infants with cleft defects plus additional defects tended to have a marginally increased risk (odds ratio = 1.76; 95% confidence interval, 1.02-3.21) in relation to maternal jobs requiring standing (> or = 75% of time). We suggest that exposure assessment be improved and defects subdivided for future studies.

Evaluation of congenital limb reduction defects in upstate New York.

Limb reduction defects (LRD), reported to the Congenital Malformations Registry in upstate New York between 1983-1987, were investigated in terms of LRD classification, parental demographics, and LRD characteristics. After excluding LRD with chromosome abnormalities, we followed guidelines developed by the European Congenital Anomaly Surveillance Consortium (EUROCAT) to classify 271 LRD into six groups based on similar patterns of embryological failure. The descriptive analysis indicated a prevalence of 0.45 per 1,000 births (stable over 5 years) for LRD diagnosed during the first 2 years of life. Among 271 LRD cases, 95 were classified as terminal transverse (35.1%), 71 as split limbs (26.2%), 36 as preaxial (13.3%), 32 as postaxial (11.8%), 26 as intercalary (9.6%), and 11 as multiple types (4.1%). In cases with multiple limb involvement (28.4%), two thirds had the same type of LRD in each limb. The multiple types and preaxial groups showed the most distinctive characteristics: they had the highest frequency of suspected syndromes, other birth defects, and syndactyly compared to the other LRD. There were no significant differences in the distribution of demographic variables among different LRD types. Consideration of the incidence and characteristics of LRD by classifying them into these distinct subgroups may be useful for evaluating possible mechanisms of malformation.

Comparison of mother's occupation and industry from the birth certificate and a self-administered questionnaire.

Maternal occupations recorded on birth certificates are a potential data source for evaluation of reproductive hazards, but may not accurately identify jobs held during the sensitive first trimester. Mothers' occupation and industry during 1 month before and 3 months after conception were reported on 1,760 mailed questionnaires. These were compared to mothers' most recent occupation and industry recorded on birth certificates. Overall, 72% of occupations and 77% of industries reported on the birth certificate agreed with that recorded on the questionnaire. Agreement was similar for mothers of normal and malformed infants. Among those that did not agree, 344 (75%) disagreed on the mother's employment status during the periconceptional period, rather than the actual occupation. For surveillance and hypothesis-generation using birth certificate data, it is important to obtain a correct description of whether the mother held a job outside the home during sensitive periods of her pregnancy.