Pounds per square inch. The pound per square inch or, more accurately, pound-force per square inch (symbol: lbf/in2; abbreviation: psi) is a unit of pressure or of stress based on avoirdupois units. It is the pressure resulting from a force of one pound-force applied to an area of one square inch:
small for gesÂ·taÂ·tionÂ·al age. Infant whose birth weight is below the tenth percentile for gestational age. small for gestational age. SGA. 1. Term describing an infant whose birth weight is at or below the 10th percentile, as correlated with the number of weeks in utero on the intrauterine growth chart.
SGA babies may be proportionately small (equally small all over) or they may be of normal length and size but have lower weight and body mass. SGA babies may be premature (born before 37 weeks of pregnancy), full term (37 to 41 weeks), or post term (after 42 weeks of pregnancy).