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.