Global Prevalence of Small for Gestational Age Births.

Fetal growth restriction is found both in babies who are preterm or full-term, and in either case has important adverse effects on subsequent survival, health, growth and development. Fetal growth restriction is usually assessed by comparing the weight of the newborn with the expected weight for the child's gestational age using less than the 10th centile of a reference population for fetal growth as the threshold for being called small for gestational age (SGA). We estimate that in 2010 32.4 million babies were born SGA in low- and middle-income countries, constituting 27% of all live births. The estimated prevalence of SGA is highest in South Asia and in Sahelian countries of Africa. India has the world's largest number of SGA births, 12.8 million in 2010, due to the large number of births and the high proportion, 46.9%, of births that are SGA. The prevalence of SGA births is approximately double the prevalence of low-birthweight births (using the common indicator of <2,500 g birthweight) globally and in the world's regions. Thus, given the adverse effects of being born SGA, even weighing 2,500 g or more, it is important that maternal, neonatal and child health programs seek and use information on gestational age as well as birthweight to appropriately assess the newborn's risks and direct care.