Prenatal ultrasound screening and congenital anomalies at birth by region: Pattern and distribution in Latvia.

Objective: The objective was to compare the ultrasound scan frequency and rate of congenital malformations between urban and rural areas.

Study Design: We conducted a population-based retrospective study using linked data from administrative data sources and register data. All singleton live births in 2018 that could be linked (n = 18,759) were included in the data analysis. Place of residence was categorized into three groups: Riga (capital city), other big cities and rural areas (including regional cities). Adjusted ORs were calculated. The multiple regression model was adjusted for maternal age, living area and prenatal screenings.

Results: Overall, 3% (n = 536) of the live-born infants were reported to have congenital malformations at birth. The proportion of congenital anomalies was, on average, 2% higher (p < 0.001) in Riga (4%, n = 334) than in the rural regions (2%, n = 93) and other cities (1%, n = 109). Women whose infants had congenital anomalies at birth had higher and statistically significant odds of having abnormal findings on ultrasound (US) screening (OR=2.3; 95% CI 1.5-3.4; p < 0.001) and undergoing invasive diagnostic tests during pregnancy (OR=2.2; 95% CI 1.4-3.5; p < 0.001). The median number of ultrasound scans during pregnancy was 3 (IQR 2) in Riga and 4 (IQR 2) in the other cities and rural regions. The top 3 types of congenital anomalies at birth were deformations of the musculoskeletal system and congenital malformations of the circulatory system and genital organs.

Conclusions: The findings of this study showed a statistically significant association between the rate of foetal anomalies and the frequency of prenatal examinations. A higher average number of US examinations per pregnancy was observed in the rural regions. Regional variations exist in the rates of specific congenital anomalies. Further studies are recommended in this field for better understanding. Surveillance systems that are able to analyse the efficiency of US examinations need to be developed for the early prenatal detection of congenital anomalies.