New insights in factors influencing growth in children born small for gestational age

__Abstract__ Small for gestational age (SGA) refers to the size of an infant at birth. It is defined as a birth weight and/ or birth length of at least two standard deviation scores (SDS) below the mean for gestational age (1, 2). SGA children can be born full-term or premature. By definition, 2.3% of all liveborn neonates are born SGA. In 2012, 175.457 infants were liveborn in the Netherlands (Central Bureau of Statistics, The Hague, The Netherlands). According to the definition, 4036 of them were born SGA. In order to determine whether a child is born SGA, accurate information on gestational age, birth weight and birth length is required, as well as an appropriate reference population (1). The term intrauterine growth retardation (IUGR) has also been used to describe infants born SGA. However, IUGR refers to a deceleration of fetal growth and does not always result in SGA birth. For example, a child with IUGR in late gestation may have a normal size at birth. Similarly, being born SGA does not necessarily mean that IUGR occurred, e.g. fetal growth may have been insufficient from the beginning of gestation. Numerous maternal, fetal, placental and environmental factors are associated with reduced fetal growth (Table 1) (3, 4). Although many factors are known, in 40% of the children no underlying cause can be determined. Nevertheless, it is important to try and identify an underlying cause since this may have consequences for health prognosis and treatment.