Experimental intra-uterine growth retardation in the guinea pig

In the Western world perinatal mortality rates have been reduced to low levels for various reasons but mainly because of better perinatal care. However morbidity is still relatively high and the concern of every parent for the quality of life of his newborn child demands continuing research into the development of the fetus and the newborn. One of the major groups of infants at risk are those that are born with a low birthweight. Approximately 5-14% of all live born children in Western Europe and the "United States have a birth weight of less than 2500 grams. Of these about two-thirds are born too early and are called "pre term" and one-third is born too small and is called "small for gestational age." Although this division seems logical it took clinicians a long time to realize the differences between these groups that hence require different treatment. ~early fifteen years ago the introduction of the so-called "intrauterine growth charts". that indicated the normal fetal growth for a certain population. offered the opportunity of categorising normal or abnormal fetal growth patterns. During recent years it has become possible to assess human fetal growth by means of ultrasound techniques and thus identify and time growth retardation in utero. At the same time follow-up studies of infants that were born small for gestational age have demonstrated that growth retardation in utero may have permanent effects on later growth and development. For ethical reasons good clinical research studies are difficult. Most research has therefore been concentrated on animals. During recent years much has become known on normal growth and development of the fetus in several species. There are numerous examples that show that fetal development is for instance under endocrine control. However the precise sequence of causal events leading to tissue differentiation late in fetal development remains unclear. Some parameters that influence fetal development may become more clear by studying abnormal fetal growth. Examples of these are the naturally occuring "runts" or the large fetuses that are frequently seen in diabetic pregnancy. Another approach to investigate the regulation of fetal growth is to experimentally reduce mean growth rate in utero. This is the approach used in this thesis which studies intrauterine growth retardation in the guinea pig and investigates some of the consequences of this condition. Such a comparative approach provides a broad background of information and thus general principles that allow specific questions of the human condition to be asked and interpreted adequately