Impact of the environment on reproduction from conception to parturition.

Consideration of environmental influences on human reproduction must include an investigation of the socioeconomic factors that play an important role in embryo-fetal development. Nutritional factors are of prime importance, and modern methods of food production and supply have led to new hazards for pregnant women. For example, pregnant women have been advised in a number of European countries not to eat liver due to the very high concentration (frequently exceeding 100,000 IU per 100 g) of vitamin A. The clear demonstration that periconceptional vitamin supplementation can dramatically reduce the recurrence rate of neural tube defects suggests that folic acid deficiency may be common even in otherwise well-nourished women. Modern methods of food production manufacture and sale have increased the risks of Salmonella and Listeria infections in pregnancy. The dangers of social drug use, especially alcohol and tobacco, are discussed. The types of adverse effect that can result from chemical exposure during the different stages of pregnancy is reviewed with a discussion of some of the problems of epidemiological studies in attempting to identify toxic chemicals. The extent of the ignorance concerning the reproductive toxicity of industrial and environmental chemicals is emphasized by the fact that data are available on only a small percentage of even the high-production volume (1000 tons/year) chemicals. The evidence of reproductive toxicity from exposure to lead, methyl mercury, polychlorinated biphenyls, polychlorinated dibenzofurans, and hexachlorobenzene are briefly reviewed. Some areas of research needs are discussed with emphasis on nutrition, food production, preparation, and storage and the new problems that may be introduced by genetic manipulation.(ABSTRACT TRUNCATED AT 250 WORDS)