Maternal serum free α- and free β-human chorionic gonadotrophin in pregnancies with insulin-dependent diabetes mellitus: Implications for screening for Down's syndrome

Authors

  • N. J. Wald,

    1. Department of Environmental and Preventive Medicine, Wolfson Institute of Preventive Medicine, The Medical College of St Bartholomew's Hospital, Charterhouse Square, London EC1M 6BQ, U.K.
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  • J. W. Densem,

    1. Department of Environmental and Preventive Medicine, Wolfson Institute of Preventive Medicine, The Medical College of St Bartholomew's Hospital, Charterhouse Square, London EC1M 6BQ, U.K.
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  • R. Cheng,

    1. Department of Environmental and Preventive Medicine, Wolfson Institute of Preventive Medicine, The Medical College of St Bartholomew's Hospital, Charterhouse Square, London EC1M 6BQ, U.K.
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  • S. Collishaw

    1. Department of Environmental and Preventive Medicine, Wolfson Institute of Preventive Medicine, The Medical College of St Bartholomew's Hospital, Charterhouse Square, London EC1M 6BQ, U.K.
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Abstract

A study was performed to investigate the concentrations of the α and β free sub-units of human chorionic gonadotrophin (free α-hCG and free β-hCG) in maternal serum between 15 and 22 weeks of pregnancy in 126 pregnancies among 92 women with insulin-dependent diabetes mellitus (IDDM). Each IDDM pregnancy was matched with two control singleton pregnancies for gestational age (same completed week) and duration of sample storage (same calendar quarter). The median free α-hCG level in the IDDM pregnancies was 0·86 multiples of the median (MOM) for pregnancies without IDDM at the same gestational age (P<0·002) (95 per cent confidence interval 0·80–0·94). The corresponding free β-hCG level was 0·96 MOM (95 per cent confidence interval 0·85–1·09). These results enable free α-hCG values to be adjusted so that antenatal screening for Down's syndrome can be performed using this marker in IDDM pregnancies as well as in non-diabetic pregnancies.

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