Randomised controlled trial of ultrasonographic screening in pregnancy.

510 of 1009 pregnant women in the Trondheim area (Norway) were randomly selected for ultrasound examination at the 19th and 32nd weeks of pregnancy in addition to routine antenatal care. Among the screened women, twins were diagnosed earlier and there were slightly fewer post-term inductions (2.8% versus 4.0%) and fewer low-weight births (2.2% versus 3.6% less than 2500 g), but none of these differences was statistically significant. There were no differences in the condition of the newborn. Small-for-gestational-age births were more often diagnosed antenatally in the screened group and the mothers received more active treatment. During pregnancy, screened women were admitted to hospital more often than unscreened women (15.5% versus 9.2%). The study revealed no adverse short-term biological effects from ultrasound. The cost of the screening programme, including associated costs such as extra hospital admissions, was about US$ 250 per pregnancy.