[Prolonged pregnancies. A comparison before and after introduction of ultrasonics]

Since 1980, when the County Hospital of Alesund introduced routine ultrasound examination in the 19th week of pregnancy to predict the date of delivery, there was a dramatic reduction in the number of pregnancies considered to be overdue. This study compares a period before routine ultrasound was introduced, when the predicted day of delivery was based upon Naegele's rule. (Period I, 1975/76, 2,683 deliveries), with a period when 97.3% of the pregnant population had an ultrasound examination to predict the day of delivery (Period II, 1984/85, 2,545 deliveries). The ultrasound examination consisted of measurement of the biparietal diameter in the 19th week of pregnancy. The postdate pregnancies were reduced from 14.8% in period I, to 1.8% in period II. The induction of labour due to postdate pregnancy was reduced from 7.2 to 1.4%. The total number of days of hospitalization for overdue pregnancy was reduced from 415 in period I, to 58 days in period II. Despite this dramatic reduction in controls and induction of overdue pregnancies, the perinatal mortality is reduced from 14 til 6.6%. This is also discussed in the article.