Screening for small for dates fetuses: a controlled trial. Routine ultrasound fetal examination in pregnancy: the 'Alesund' randomized controlled trial. Effect of prenatal ultrasound screening on perinatal outcome. RADIUS Study Group. A randomized controlled trial in a hospital population of ultrasound measurement screening for the small for dates baby. Routine ultrasonography in utero and school performance at age 8-9 years. Effects of frequent ultrasound during pregnancy: a randomised controlled trial. Third trimester placental grading by ultrasonography as a test of fetal wellbeing.
In the hope of reducing perinatal risks associated with retardation of intrauterine growth a previously described two stage ultrasound screening schedule was evaluated by a controlled trial in 877 women with low risk single pregnancies. The two stages of ultrasound examination were an assessment of gestational age during early pregnancy followed by measurement of length from crown to rump and area of trunk at between 34 and 36 weeks' gestation. The product of crown to rump length and trunk area was calculated. The sensitivity of this schedule in identifying in advance 94% of babies who were small for dates at birth, with 90% specificity, and the speed and simplicity of measurement confirmed the accuracy and feasibility of two stage ultrasonography as a screening procedure. The controlled trial did not, however, show any benefit from its routine application in these low risk pregnancies. To evaluate the possible benefits of the routine use of ultrasound screening in pregnancy.
                A randomized controlled trial was designed to detect a 50% difference in the incidence of induction for apparent post-term pregnancies between women who were screened with ultrasound and unscreened women. A total of 1628 pregnant women from the general population were included. Eight hundred and twenty-five were allocated to an ultrasound examination at the 18th and 32nd week of pregnancy in addition to receiving routine antenatal care. The remaining 803 women received standard antenatal care, but could only be referred for ultrasound examination on clinical indication.
                The incidence of induced labor due to apparent post-term pregnancies was approximately 70% lower in the ultrasound-screened group. Inductions from all causes were also less frequent among ultrasound-screened women. There were six perinatal deaths among the screened and seven among the controls after excluding three lethal malformations among the controls. There was no difference in Apgar score after 1 min, but the proportion with Apgar score less than 8 after 5 min was lower among the screened group (P = 0.04). The need for positive pressure ventilation for more than 1 min was lower among the screened group (P = 0.02). Birth weight was slightly higher in the screened group (39 g), but the difference was not statistically significant. Among the controls three pairs of twins remained undiagnosed until the mothers were admitted to the hospital in labor at between 36 and 38 weeks gestation.
                These results suggest that for women who were screened with ultrasound, obstetricians were less likely to induce labor due to apparent post-term pregnancy, than for women who were not screened. All 10 pairs of twins in the screened group were diagnosed at the routine examination. These data also suggest that perinatal morbidity might be slightly lower in the screened group. Many clinicians advocate routine ultrasound screening during pregnancy to detect congenital anomalies, multiple-gestation pregnancies, fetal growth disorders, placental abnormalities, and errors in the estimation of gestational age. However, it is not known whether the detection of these conditions through screening leads to interventions that improve perinatal outcome.
                We conducted a randomized trial involving 15,151 pregnant women at low risk for perinatal problems to determine whether ultrasound screening decreased the frequency of adverse perinatal outcomes. The women randomly assigned to the ultrasound-screening group underwent one sonographic examination at 15 to 22 weeks of gestation and another at 31 to 35 weeks. The women in the control group underwent ultrasonography only for medical indications, as identified by their physicians. Adverse perinatal outcome was defined as fetal death, neonatal death, or neonatal morbidity such as intraventricular hemorrhage.
                The mean numbers of sonograms obtained per woman in the ultrasound-screening and control groups were 2.2 and 0.6, respectively. The rate of adverse perinatal outcome was 5.0 percent among the infants of the women in the ultrasound-screening group and 4.9 percent among the infants of the women in the control group (relative risk, 1.0; 95 percent confidence interval, 0.9 to 1.2; P = 0.85). The rates of preterm delivery and the distribution of birth weights were nearly identical in the two groups. The ultrasonographic detection of congenital anomalies had no effect on perinatal outcome. There were no significant differences between the groups in perinatal outcome in the subgroups of women with post-date pregnancies, multiple-gestation pregnancies, or infants who were small for gestational age.
                Screening ultrasonography did not improve perinatal outcome as compared with the selective use of ultrasonography on the basis of clinician judgment. Poor fetal growth is an important cause of perinatal mortality and morbidity. Based on the hypothesis that early diagnosis of fetal growth problems leads to more appropriate management and therefore, improved outcome, a randomized controlled trial of ultrasound measurement was performed on 1,528 women booked through a hospital antenatal clinic. This compared a number of perinatal outcomes between the group who had a routine 2-stage examination (early dating and 34-week scan) and a group who had only a dating scan and then additional scans as generated by their clinical situations. No significant differences could be found between the groups when these perinatal outcomes were considered. These results mirror previously published randomized controlled trials. Selection of women for third trimester ultrasound examination for suspected fetal growth problems should be based on careful clinical assessment and should not be routine. Most fetuses in developed countries are exposed in utero to diagnostic ultrasound examination. Many pregnant women express concern about whether the procedure harms the fetus. Since most routine ultrasound examinations are done at weeks 16-22, when the fetal brain is developing rapidly, effects on neuronal migration are possible. We have sought an association between routine ultrasonography in utero and reading and writing skills among children in primary school. At the age of 8 or 9 years, children of women who had taken part in two randomised, controlled trials of routine ultrasonography during pregnancy were followed-up. The women had attended the clinics of 60 general practitioners in central Norway during 1979-81. The analysis of outcome was by intention to treat: 92% of the "screened" group had been exposed to ultrasound screening at weeks 16-22, and 95% of controls had not been so exposed, but there was some overlap. 2428 singletons were eligible for follow-up, and the school performance of 2011 children (83%) was assessed by their teachers on a scale of 1-7; the teachers were unaware of ultrasound exposure status. A subgroup of 603 children underwent specific tests for dyslexia. There were no statistically significant differences between children screened with ultrasound and controls in the teacher-reported school performance (scores for reading, spelling, arithmetic, or overall performance). Results from the dyslexia test sample showed no differences between screened children and controls in reading, spelling, and intelligence scores, or in discrepancy scores between intelligence and reading or spelling. The test results classified 21 of the 309 screened children (7% [95% confidence interval 3-10%]) and 26 of the 294 controls (9% [4-12%]) as dyslexic. The risk of having poor skills in reading and writing was no greater for children whose mothers had been offered routine ultrasonography than for those whose mothers had not been offered the procedure. Despite widespread application of ultrasound imaging and Doppler blood flow studies, the effects of their frequent and repeated use in pregnancy have not been evaluated in controlled trials. From 2834 women with single pregnancies at 16-20 weeks gestation, 1415 were selected at random to receive ultrasound imaging and continuous-wave Doppler flow studies at 18, 24, 28, 34, and 38 weeks gestation (the intensive group) and 1419 to receive single ultrasound imaging at 18 weeks (the regular group). Outcome data was obtained from 99% of women who entered the study. The only difference between the two groups was significantly higher intrauterine growth restriction in the intensive group, when expressed both as birthweight < 10th centile (relative risk 1.35; 95% confidence interval 1.09 to 1.67; p = 0.006) and birthweight < 3rd centile (relative risk 1.65; 95% confidence intervals 1.09 to 2.49; p = 0.020). While it is possible that this finding was a chance effect, it is also plausible that frequent exposure to ultrasound may have influenced fetal growth. Repeated prenatal ultrasound imaging and Doppler flow examinations should be restricted to those women to whom the information is likely to be of clinical benefit. In a study of 2000 unselected pregnant women the development of a mature placental appearance (grade 3) on ultrasonography by 34-36 weeks' gestation, observed in 15% of cases, was associated with maternal smoking, low parity, low maternal age, and being white. These women had an increased risk of problems during labour and their babies had an increased risk of low birth weight, poor condition at birth, and perinatal death. The women were randomly allocated to two groups: in one group the result of the placental grading was reported to the clinician responsible for care; in the second the result was noted but not reported. There was a significant decrease in the risk of perinatal death in the group where the grading was known. This reduction was responsible for a difference in the principal outcome index, a heterogeneous group of measures of mortality and morbidity, but this difference was not significant. This study alone does not justify routine late scanning, and further, larger trials are required. Nevertheless, the results do provide a basis for the reporting of placental grading when ultrasound examination is performed during the third trimester.
Based on existing evidence, routine late pregnancy ultrasound in low-risk or unselected populations does not confer benefit on mother or baby. It may be associated with a small increase in caesarean section rates. There is a lack of data about the potential psychological effects of routine ultrasound in late pregnancy, and limited data about its effects on both short- and long-term neonatal and childhood outcome. Placental grading in the third trimester may be valuable, but whether reported results are reproducible remains to be seen, and future research of late pregnancy ultrasound should include evaluation of placental textural assessment.