Informed choice in genetic screening for thalassaemia during pregnancy: audit from a national confidential inquiry

Abstract

Objective: National audit of informed choice in antenatal screening for thalassaemia.

Design: Audit from the UK Confidential Enquiry into Counselling for Genetic Disorders.

Setting: Thalassaemia module of the UK Confidential Enquiry into Counselling for Genetic Disorders.

Subjects: 138 of 156 couples who had had a pregnancy affected by a major beta thalassaemia from 1990 to 1994.

Main outcome measures: How and when genetic risk was identified for each couple, and whether and when prenatal diagnosis was offered.

Results: Risk was detected by screening before or during the first pregnancy in 49% (68/138) of couples and by diagnosis of an affected child in 28% (38/138) of couples. Prenatal diagnosis was offered in 69% (274/400) of pregnancies, ranging from 94% (122/130) for British Cypriots to 54% (80/149) for British Pakistanis and from 90% in the south east of England to 39% in the West Midlands. Uptake of prenatal diagnosis was 80% (216/274), ranging from 98% (117/120) among British Cypriots in either the first or second trimester to 73% (35/48) among British Pakistanis in the first trimester and 39% (11/28) in the second trimester. A demonstrable service failure occurred in 28% (110/400) of pregnancies, including 110 of 126 where prenatal diagnosis was not offered and 48 of 93 that ended with an affected liveborn infant.

Conclusion: Although antenatal screening and counselling for haemoglobin disorders are standard practices in the United Kingdom, they are delivered inadequately and inequitably. An explicit national policy is needed, aiming to make prenatal diagnosis in the first trimester available to all couples and including ongoing national audit.

Figure 1

Distribution and ethnic group of 138 study couples by 1991 regional health authority or country. Other=Italian or other Mediterranean, Chinese or other South East Asian, African-Caribbean, and Middle Eastern

Figure 2

Availability of information and choice to 138 couples at risk of a thalassaemic pregnancy, from national inquiry into genetic counselling, ranked in order of total number of pregnancies. Each column represents one woman, and shows all viable pregnancies at risk since 1980 with antenatal care in the United Kingdom

Figure 3

Uptake of prenatal diagnosis by ethnic group and gestation at counselling. Fisher's exact test for British Pakistanis showed a significant difference (P=0.004) in proportion requesting prenatal diagnosis in first versus second trimester

Figure 4

Outcome of 403 conceptions at risk (400 pregnancies) by region. Regional differences are highly significant (χ² test on 8 df=96.87, P<0.001)