Objective To compare the antenatal detection rate of malformations in chromosomally normal fetuses between a strategy of offering one routine ultrasound examination at 12 gestational weeks (gws) and a strategy of offering one routine examination at 18 gws.Design Randomised controlled trial.Setting Multicentre trial including eight hospitals.Population A total of 39 572 unselected pregnant women.Methods Women were randomised either to one routine ultrasound scan at 12 (12-14) gws including nuchal translucency (NT) measurement or to one routine scan at 18 (15-22) gws. Anomaly screening was performed in both groups following a check-list. A repeat scan was offered in the 12-week scan group if the fetal anatomy could not be adequately seen at 12-14 gws or if NT was ‡3.5 mm in a fetus with normal or unknown chromosomes.Main outcome measures Antenatal detection rate of malformed fetuses.Results The antenatal detection rate of fetuses with a major malformation was 38% (66/176) in the 12-week scan group and 47% (72/152) in the 18-week scan group (P = 0.06). The corresponding figures for detection at <22 gws were 30% (53/176) and 40% (61/152) (P = 0.07). In the 12-week scan group, 69% of fetuses with a lethal anomaly were detected at a scan at 12-14 gws.Conclusions None of the two strategies for prenatal diagnosis is clearly superior to the other. The 12-week strategy has the advantage that most lethal malformations will be detected at <15 gws, enabling earlier pregnancy termination. The 18-week strategy seems to be associated with a slightly higher detection rate of major malformations, although the difference was not statistically significant.

Objective To compare the rate of prenatal diagnosis of heart malformations between two policies of screening for heart malformations.Design Randomised controlled trial.Setting Six university hospitals, two district general hospitals.Sample A total of 39 572 unselected pregnancies randomised to either policy.Methods The 12-week policy implied one routine scan at 12 weeks including measurement of nuchal translucency (NT), and the 18-week policy implied one routine scan at 18 weeks. Fetal anatomy was scrutinised using the same check-list in both groups, and in both groups, indications for fetal echocardiography were ultrasound findings of any fetal anomaly, including abnormal fourchamber view, or other risk factors for heart malformation. In the 12-week scan group, NT ‡3.5 mm was also an indication for fetal echocardiography.Main outcome measure Prenatal diagnosis of major congenital heart malformation.Results In the 12-week scan group, 7 (11%) of 61 major heart malformations were prenatally diagnosed versus 9 (15%) of 60 in the 18-week scan group (P = 0.60). In four (6.6%) women in the 12-week scan group, the routine scan was the starting point for investigations resulting in a prenatal diagnosis versus in 9 (15%) women in the 18-week scan group (P = 0.15). The diagnosis was made £22 weeks in 5% (3/61) of the cases in the 12-week scan group versus in 15% (9/60) in the 18-week scan group (P = 0.08).Conclusions The prenatal detection rate of major heart malformations was low with both policies. The 18-week scan policy seemed to be superior to the 12-week scan policy, although the differences in prenatal detection rates were not statistically significant.

Objectives To determine the accuracy of established ultrasound dating formulae when used at 12-14 weeks of gestation. Methods One-hundred and sixty-seven singleton pregnancies conceived after in-vitro

Objectives To determine the accuracy of established ultrasound dating formulae when used at 12-14 and 15-20

Objective  To analyse the association between fetal size at time of dating ultrasound and risk for preterm delivery and small‐for‐gestational‐age (SGA) birth and to evaluate if timing of ultrasound, that is before 14 weeks of gestation or after 16 weeks affects this association. Design  Retrospective cohort study. Setting  Ultrasound departments of Ultragyn, Stockholm, Sweden. Population  A total of 28 776 singleton pregnancies dated between 1998 and 2004. Methods  Obstetric outcome was assessed through linkage of the cohort to the Swedish Medical Birth Register. Main outcome measures  Risks of preterm delivery, low birthweight for gestational age, pre‐eclampsia, asphyxia, respiratory distress, instrumental delivery, caesarean section, and postterm birth were calculated for the groups dated early and late. Results  When the expected date of delivery was postponed after ultrasound dating by 7 days or more, there was an increased risk for preterm delivery and pre‐eclampsia in the late dating group (OR 1.49, 95% CI 1.27–1.73 and OR 1.27, 95% CI 1.02–1.60, respectively) but not in the early dating group. In both dating groups, there was an increased risk for SGA birth (OR 1.77, 95% CI 1.13–2.78 and OR 2.09, 95% CI 1.59–2.73, respectively) There was no increased risk for any of the other diagnoses. Conclusion  Our study gives further support to the notion that intrauterine growth restriction may be present as early as the first trimester. Accordingly, our study also suggests that surveillance of pregnancies with postponed estimated date of delivery may provide means for increased detection of fetal growth restriction.