A study was carried out to assess the effect on the outcome of pregnancy of iron overdose and its treatment with desferrioxamine. Sixty-eight cases were drawn from those reported to the United Kingdom National Poisons Information Centre and the Teratology Information Service at Guy's Hospital, London, and follow-up was obtained in 51 of these. Two were subsequently reported not to be pregnant and there were 49 records of pregnant patients who took iron overdoses and where outcome of the pregnancy was known. Twenty-five of these patients were treated with desferrioxamine. In 48 of the 49 patients the dose of iron allegedly taken was known and in 28 (60%) was over 20 mg kg-1, sufficient to put them at risk of toxicity. In the 36 whose serum iron levels were measured, 20 patients had levels in excess of 60 mumol l-1, indicating a risk of moderate or severe toxicity. Of the 49 pregnancies, 43 resulted in live babies, two had spontaneous abortions and there were four elective terminations. Of the live babies, three were premature, two of whom had problems, and there were three other babies with abnormalities. All babies with malformations were associated with overdoses after the first trimester and so the malformations cannot be directly related to the overdose. A total of 25 patients received desferrioxamine of whom two had malformed babies, but the desferrioxamine can be excluded as a cause. There was no correlation between the serum iron levels and the birthweights. In conclusion, iron overdose in pregnancy can be fatal and antidote treatment if appropriate should not be withheld.(ABSTRACT TRUNCATED AT 250 WORDS)