Page 12

and functional deficiency (e.g., neurological, respiratory, and immune deficiencies) in the offspring (Wilson 1973).

Known causes of reproductive and developmental disorders include genetic defects; maternal metabolic imbalances; infection; and occupational, therapeutic, and environmental exposures to chemical and physical agents. This report primarily addresses reproductive and developmental defects that might be attributable to chemical and other agent occupational exposures.

The number of individuals affected by reproductive disorders is difficult to assess, and few population-based data are available for either men or women. Noticeably absent are data on fecundity and fertility impairments affecting men and only limited information on male-mediated developmental outcomes exists. Population-based data for impaired female fertility are available for select endpoints from the National Surveys of Family Growth (NSFG), which are conducted periodically and most recently in 1995. Data from the NSFG show that 6.2 million women (10.2%) between the ages of 15 and 44 in the United States had impaired fertility in 1995 (Stephen 1996). This number was estimated to increase to 6.3 million women in 2000 (Stephen and Chondra 1998). Other reproductive disorders in females that impact fecundity include endometriosis and polycystic ovarian syndrome (PCOS). The prevalence of endometriosis in women of reproductive age is reported to be 10% (Houston 1984; Olive and Schwartz 1993), and no population-based prevalence data exist for PCOS.

With respect to developmental outcomes, population-based data are available regarding the prevalence of birth defects. Approximately 2-3% of infants are born with major birth defects (Holmes 1997). The full impact of prenatal testing on the prevalence of birth defects has not been delineated. The prevalence of birth defects increases (approximately 5%) when all defects (i.e., major and minor) are included. However, identifying the prevalence of minor defects is problematic, given differences in clinical assessment, recognition and reporting of defects, and variations across state-birth-defects registries in the recording of minor defects. Other developmental outcomes that need to be considered in assessing developmental toxicity include fetal and infant growth and developmental disabilities during infancy and childhood. Boyle et al. (1994), citing data from the 1988 National

The National Academies of Sciences, Engineering, and Medicine
500 Fifth St. N.W. | Washington, D.C. 20001

Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement