Audit of prenatal diagnosis for haemoglobin disorders in the United Kingdom: the first 20 years

Abstract

Objectives: To audit services for prenatal diagnosis for haemoglobin disorders in the United Kingdom.

Design: Comparison of the annual number of cases recorded in a United Kingdom register of prenatal diagnoses for haemoglobin disorders, with the annual number of pregnancies at risk of these disorders, by ethnic group and regional health authority. The number of pregnancies at risk was estimated using data on ethnic group from the 1991 census and data from the United Kingdom thalassaemia register, which records the number of babies born with thalassaemia.

Setting: The three national prenatal diagnosis centres for haemoglobin disorders.

Subjects: 2068 cases of prenatal diagnosis for haemoglobin disorders in the United Kingdom from 1974 to 1994.

Main outcome measures: Utilisation of prenatal diagnosis by risk, ethnic group, and regional health authority. Proportion of referrals in the first trimester and before the birth of any affected child.

Results: National utilisation of prenatal diagnosis for haemoglobin disorders was around 20%. During the past 10 years it has remained steady at about 50% for thalassaemias and risen from 7% to 13% for sickle cell disorders. Utilisation for sickle cell disorders varies regionally from 2% to 20%. Utilisation for thalassaemias varies by ethnic group. It is almost 90% for Cypriots and ranges regionally for British Pakistanis from 0% to over 60%. About 60% of first prenatal diagnoses are done for couples without an affected child. Less than 50% of first referrals are in the first trimester.

Conclusions: National utilisation of prenatal diagnosis for haemoglobin disorders is far lower than expected, and there are wide regional variations. A high proportion of referrals are still in the second trimester and after the birth of an affected child. The findings point to serious shortcomings in present antenatal screening practice and in local screening policies and to inadequate counselling resources, especially for British Pakistanis.