Delay between pregnancy confirmation and sickle cell and [corrected] thalassaemia screening: a population-based cohort study

Abstract

Background: Antenatal sickle cell and thalassaemia screening sometimes occurs too late to allow couples a choice regarding termination of affected fetuses. The target gestational age for offering the test in the UK is 10 weeks.

Aim: To describe the proportion of women screened before 70 days' (10 weeks') gestation and the delay between pregnancy confirmation in primary care and antenatal sickle cell and thalassaemia screening.

Design of study: Cohort study of reported pregnancies.

Setting: Twenty-five general practices in two UK inner-city primary care trusts offering universal screening.

Method: Anonymised data on all pregnancies reported to participating general practices was collected for a minimum of 6 months.

Results: There were 1441 eligible women intending to proceed with their pregnancies, whose carrier status was not known. The median (interquartile range [IQR]) gestational age at pregnancy confirmation was 7.6 weeks (6.0-10.7 weeks) and 74% presented before 10 weeks. The median gestational age at screening was 15.3 weeks (IQR = 12.6-18.0 weeks), with only 4.4% being screened before 10 weeks. The median delay between pregnancy confirmation and screening was 6.9 weeks (4.7-9.3 weeks) After allowing for practice level variation, there was no association between delay times and maternal age, parity, and ethnic group.

Conclusion: About 74% of women consulted for pregnancy before 10 weeks' gestation but fewer than 5% of women were screened before the target time of 10 weeks. Reducing the considerable delay between pregnancy confirmation in primary care and antenatal sickle cell and thalassaemia screening requires methods of organising and delivering antenatal care that facilitate earlier screening to be developed and evaluated.

Figure 1

Distributions for gestational age at first pregnancy confirmation and sickle cell and thalassaemia screening for women whose pregnancies were confirmed before 26 weeks gestation.