Antenatal screening for small-for-gestational-age, using risk factors and measurements of the symphysis-fundus distance--6 years of experience.

In a previous prospective study, we outlined a screening programme aiming at detection of a high-risk group for small-for-gestational-age (SGA) pregnancies. The present study evaluates this screening programme in all women delivering at the hospital in 1 year and in all women delivering SGA infants during a 6-year period. When screening for SGA, using symphysis-fundus measurements together with risk factors, the false positive rates were unacceptably high. When only using repeated measurements of the symphysis-fundus distance the results were more acceptable (sensitivity 59%, specificity 97%, positive predictive value 15%). Between 1980 to 1985, 18,604 live singleton infants were born. Altogether 156 infants were assessed as SGA (birthweight for gestational age less than -2 S.D.). Two antenatal records from SGA pregnancies were missing and in 14 pregnancies, antenatal detection of SGA would not have improved the prognosis of the infants (severe congenital malformations or preterm delivery due to maternal diseases). Thus, of 140 SGA pregnancies in focus pathological symphysis-fundus measurements occurred in 63%. It is concluded that by repeated measurements of the symphysis-fundus distance, it is quite possible to form a high-risk group for SGA. In this high-risk group, including less than 4% of the pregnant population, the majority of SGA pregnancies are found.