The Scandinavian small-for-gestational age (SGA) pregnancy and birth cohort – A source to continual insight into fetal growth restriction and long term physical and neurodevelopmental health in mother and offspring

Abstract

Human in utero growth restriction (IUGR) is associated with an increased risk for perinatal mortality and morbidity among newborns and infants. To pursue this challenge, a Request For Proposals (RFP) was issued in 1983 by The U.S. Epidemiology and Biometry Research Program at the National Institute of Child Health and Human Development (NICHD). A consortium was set up at the universities and university hospitals in Trondheim, Bergen (Norway) and Uppsala (Sweden) and was funded by the NICHD to conduct the Scandinavian Successive Small-for-Gestational Age (SGA) pregnancy and birth outcome study. The study design included a comprehensive biobank with maternal and cord serum samples, placental tissue, and a multitude of data collected from interviews, questionnaires, and clinical examinations. The SGA cohort study involved 6,354 Caucasian pregnant women in the three study sites who expected their second or third child from 1986-88. The study women were screened in early second trimester and mothers who had an increased risk to deliver a smaller than expected newborn were followed in detail through the second half of pregnancy and at birth. Selected children were screened several times through their first and up to five years of age. Moreover, a highly selected subgroup in Trondheim has been followed at 14, 19, and 26 years’ age. Almost thirty years later, we have searched the body of scientific publications that originated from this cohort study in an attempt to assess if and to what extent the main aims and objectives were achieved and to summarize the overall outcomes. The SGA cohort has resulted in close to 100 published papers in peer reviewed journals and some 40 graduate and undergraduate degrees. Risk factors of SGA, like maternal smoking, low prepregnancy weight and education attainment, and a previous SGA birth outcome were confirmed. Conversely, no totally new and unknown risk factors were identified. Serial ultrasound measures have enabled a distinction between SGA with restricted and normal intrauterine growth, and has further indicated that being born SGA is mainly a problem in combination with IUGR. Further, the consequences of IUGR are more pronounced at adolescence and young adulthood than at five years of age. An increased understanding of the pathogenesis of different categories of growth restriction is essential to recognize and diagnose IUGR properly, and to reduce the perinatal mortality and morbidity from SGA. Moreover, SGA is a significant predictor at follow-up of the child. An up to date biobank has ensured the quality of data and biological samples, and has been crucial for the outcome of the entire SGA study. It continues to be a valuable resource in future research.