We have investigated the prevalence of positive serology for coeliac disease in pregnant women, using the IgA anti-endomysium antibody test. Five of 216 pregnant women with a haemoglobin less than 11 g/dl were positive, compared to 0/350 with haemoglobin > or = 11 g/dl. Four of these five had low plasma ferritin levels, indicative of iron deficiency anaemia; the fifth was borderline normal. We found no association between positive coeliac disease serology and folate deficiency. None of thirty mothers of children born with neural tube defects were IgA anti-endomysium antibody positive. This study has identified a very high prevalence of occult coeliac disease in pregnancy and a strong association with anaemia. We advise that in cases with a haemoglobin of less than 11 g/dl in pregnancy, coeliac disease should be excluded.