Objective To evaluate whether a nationwide prenatal anomaly screening programme improves detection rates of univentricular heart (UVH) and transposition of great arteries (TGA), and whether maternal risk factors for severe fetal heart disease affect prenatal detection. Design Population‐based cohort study. Setting Nationwide data from Finnish registries 2004–14. Population A total of 642 456 parturients and 3449 terminated pregnancies due to severe fetal anomaly. Methods Prenatal detection rates were calculated in three time periods (prescreening, transition and screening phase). The effect of maternal risk factors (obesity, in vitro fertilisation, pregestational diabetes and smoking) was evaluated. Main outcome measures Change in detection rates and impact of maternal risk factors on screening programme efficacy. Results In total, 483 cases of UVH and 184 of TGA were detected. The prenatal detection rate of UVH increased from 50.4% to 82.8% and of TGA from 12.3% to 41.0% (P < 0.0001). Maternal risk factors did not affect prenatal detection rate, but detection rate differed substantially by region. Conclusions A nationwide screening programme improved overall UVH and TGA detection rates, but regional differences were observed. Obesity or other maternal risk factors did not affect the screening programme efficacy. The establishment of structured guidelines and recommendations is essential when implementing the screening programme. In addition, a prospective screening register is highly recommended to ensure high quality of screening. Tweetable abstract Implementation of a nationwide prenatal anomaly screening improved detection rates of UVH and TGA.

The total prevalence of hypoplastic left heart syndrome was significantly higher in CDH patients than in the general population in Finland. Prenatal detection rate for heart defects in CDH patients was 41%. Major extra-cardiac malformations were more common than previously reported. The prognosis of CDH with major heart defects remained poor.

Introduction: Newborn infants with transposition of the great arteries (d-TGA) need immediate care for an optimal outcome. This study comprised a nationwide 11-year population-based cohort of d-TGA infants, and assessed whether the implementation of a nationwide systematic fetal screening program, or other perinatal, or perioperative factors, are associated with mortality or an increased need for hospital care. Material and methods: The national cohort consisted of all live-born infants with simple d-TGA (TGA ± small ventricular septal defect, n = 127) born in Finland during 2004-2014. Data were collected from six national registries. Prenatal diagnosis and perinatal and perioperative factors associated with mortality and length of hospitalization were evaluated. Results: Preoperative mortality was 7.9%, and the total mortality was 8.7%. The prenatal detection rate increased after introducing systematic fetal anomaly screening from 5.0% to 37.7% during the study period (P < .0001), but the total mortality rate remained unchanged. All prenatally diagnosed infants (n = 27) survived. Lower gestational age (odds ratio 0.68, P = .012) and higher maternal age at birth (odds ratio 1.16, P = .036) were associated with increased mortality in multivariable analysis. Older infant age at time of operation (P = .002), longer aortic clamp time (P < .001), and higher maternal body mass index (P = .027) were associated with longer initial hospital stay. An extended need for hospital care during the first year of life was multi-factorial. Conclusions: In our cohort, none of the prenatally diagnosed d-TGA infants died. As a result of the limited prenatal detection rates, however, the sample size was insufficient to reach statistical significance. The d-TGA infants born with lower gestational age and to older mothers had increased mortality.