Coverage of antenatal haemoglobinopathy screening in the Capital Region of Denmark: a laboratory-based evaluation of screening implementation.

Haemoglobinopathies are increasingly encountered in low-prevalence countries due to migration, placing greater demands on effective antenatal screening pathways. In Denmark, antenatal haemoglobinopathy screening is offered through general practice to women considered at high risk. We evaluated the implementation of this screening programme in the Capital Region of Denmark during 2022-2023 and estimated the national burden of haemoglobinopathy carriers. Using laboratory data from the Danish Red Blood Cell Centre, we identified women aged 15-40 years who underwent diagnostic haemoglobinopathy testing after referral from general practice. These data were compared with municipality-level numbers of births in the operational at-risk population obtained from Danish nationwide registries to estimate screening coverage. National carrier estimates were derived from country-specific carrier frequencies combined with Danish population data. Based on these estimates, approximately 57,103 individuals in Denmark were expected to be haemoglobinopathy carriers, with six countries of origin representing over half of this population. In the Capital Region, 4389 women were tested compared with 9359 births in the operational at-risk population, corresponding to an estimated coverage of 46.9%. Coverage ranged from 10.8% in Helsingør to 92.7% in Ishøj. Across the Capital Region, 193 of 618 registered general practice clinics did not order a haemoglobinopathy test during 2022-2023, with substantial variation between municipalities. These findings indicate a substantial haemoglobinopathy carrier burden in Denmark and marked geographical variation in the implementation of antenatal screening in the Capital Region. The current screening programme appears to be applied inconsistently across municipalities and general practice clinics.