Objective To assess the utility of biochemical antenatal screening for Down's syndrome in a socioeconomically deprived area with a high proportion of Asian women from the Indian Subcontinent.

Design Audit of Down's syndrome biochemical screening service over a four-year period.

Setting Teaching hospital and community antenatal clinic in inner city Birmingham.

Population Women booked between October 1992 and December 1996.

Methods Blood for screening was collected between 14 and 21 weeks gestation, alpha-fetoprotein and intact human chorionic gonadotrophin were measured in serum and the risk of Down's syndrome was calculated.

Main outcome measures Uptakes of screening and amniocentesis, screen positive rate, odds of being affected given a positive result, miscarriages associated with amniocentesis offered following a high risk result, detection rate, number of Down's cases prevented and a cost analysis.

Outcome measures were compared between Asians and Caucasians.

Results Overall 11,974 women (71%) accepted serum screening.

The screen positive rate was 8.3% in Asians and 5.0% in Caucasians.

The uptake of amniocentesis in women following a high risk result was 54% overall (35% Asian, 67% Caucasian).

Nineteen cases of Down's syndrome were identified, of which 13 occurred in women who opted for biochemical screening.

The detection rate of the biochemical screening programme was 85% (11/13). (...)