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M. Hack

Correspondence: Dr Maureen Hack

Case Western Reserve University, Rainbow Babies & Childrens Hospital, University Hospitals of Cleveland, 11100 Euclid Ave., Cleveland, OH 44106-6010, USA

Studies of the long-term effects of intrauterine growth retardation on mental performance and behavior are reviewed. The results of the majority of studies suggest that, if effects of prematurity and of other associated complicating factors are controlled for, effects of IUGR per se, that can sometimes be demonstrated at an earlier age, become diluted by socio-environmental conditions at later stages in life and no longer appear to have a detrimental effect on mental and behavioral outcomes in adolescence and adulthood.

Studies of the long-term effects of intrauterine growth retardation (IUGR) on mental performance and behavior have provided varying and often conflicting results. This is mainly due to the heterogeneity of the populations that have been studied, including different definitions and varying causes of IUGR, differences in perinatal and neonatal complications associated with the gestational age of the child, and differences in the quality of neonatal care. Initial reports of the consequences of IUGR included children with major congenital malformations and children with intrauterine infections, who are known to have very poor developmental outcomes (Allen, 1984; Warkany et al, 1966). Furthermore postnatal conditions may confound the effects of IUGR on later mental performance and behavior. These include subnormal nutrition and growth during infancy and early childhood, and the social and environmental conditions of the family (Allen, 1984; Smeriglio, 1989). Reported heterogeneity of outcomes of IUGR is further influenced by the fact that some studies are population based, whereas others include only selected high-risk hospital populations. Many studies include both preterm and term children, and some include multiple births. The loss to follow-up sometimes exceeds 50%, thus populations followed might not be representative of the original population.

The majority of available reports of adolescent and adult outcomes of IUGR populations pertain to births that occurred prior to the development of current methods of perinatal and neonatal care, when infant mortality was very high. Furthermore, between 1940 and 1960, various practices of newborn care caused iatrogenic sequelae that had a detrimental effect on outcomes. These included prolonged starvation of babies, unrestricted use of oxygen that resulted in blindness, followed by a period of restricted use of oxygen resulting in higher death rates and cerebral palsy, and the widespread use of antibiotics, especially sulfa drugs causing kernicterus and streptomycin causing dearness (Hack et al, 1979; Douglas and Gear, 1976). Current methods of perinatal care include antenatal surveillance of intrauterine growth failure and associated fetal distress, optimal timing of delivery, adequate neonatal resuscitation and the prevention and treatment of neonatal complications associated with IUGR such as hypoglycemia and polycythemia (Kramer et al, 1990; Hawdon et al, 1990; Tenovuo et al, 1988). There is currently a greater awareness of the importance of the home environment and socioeconomic status of the family as determinants of childhood and adult outcomes (Sameroff et al, 1993).

This report will review the published literature on the mental performance and behavior of adolescent and adult persons who experienced intrauterine growth retardation.