Potato avoidance during pregnancy in women with a previous infant with either anencephaly and/or spina bifida.

This investigation is a direct attempt to test Renwick's (1972) hypothesis that 95% of anencephaly and spina bifida (ASB) is preventable by the avoidance of potatoes during pregnancy. Although the numbers involved in the study are small, the investigation fails to support the concept that short-term avoidance of potatoes before conception and throughout pregnancy in women who have had a previous ASB infant reduces the recurrence risk. In the potato-free group, of 23 pregnancies which went to term two infants had ASB (8-7%); whereas in the non-potato-free group, of 56 which went to term two infants had ASB (3-6%). The recurrence risk in both groups was about 5%. The incidence of ASB in the groups shows no significant difference (P = 0-58) and in the potato-free group was not reduced by 95% as postulated by Renwick.