Risk factors for recurrent small-for-gestational-age birth.

The factors associated with recurrent small-for-gestational-age birth (R-SGA) have not been previously studied in a multiracial population. This is a retrospective cohort study of 5932 black and white women who had consecutive singleton first and second births in a Midwestern metropolis, from 1995 through 2004, to measure the risk and determine the factors associated with R-SGA. The rates for second-born small-for-gestational-age birth and R-SGA were 10.3% and 4.0%, respectively. Compared with mothers of firstborns who were appropriate for gestational age, mothers of firstborns who were small for gestation age had a higher risk of second-born small-for-gestational-age infants (relative risk [RR] = 3.93; 95% confidence interval [95% CI] = 3.36 to 4.59). Among those with firstborns who were small for gestational age, the odds ratio (OR) and 95% CI of R-SGA were higher for lean body mass index + poor gain (2.83; 1.20 to 6.69), blacks (1.58; 1.09 to 2.29), and smokers (1.61; 1.05 to 2.47). R-SGA occurs in 4% of second births and is responsible for 40% of second-born small-for-gestational-age infants. R-SGA is potentially preventable because of its association with potentially modifiable factors such as smoking and weight gain in pregnancy.