To understand the periconceptional use of folic acid and its association with selected characteristics in northern China.

As part of a population-based case–control study on external structural birth defects, we analysed periconceptional use of folic acid among control mothers.

The study was conducted in four counties (Pingding, Xiyang, Taigu and Zezhou) in Shanxi Province of northern China.

The subjects in this study were the control mothers, who were interviewed between January 2003 and May 2005.

Of the 480 respondent mothers, 49 women (10.2%) reported ever using folic acid supplements, and only 16 women (3.3%) used it periconceptionally. The rates of any use and periconceptional use did not change significantly with study year. Periconceptional use of folic acid was significantly increased among women with more than high school education (odds ratio (OR) = 4.57, P < 0.10), women who were not farmers (OR = 4.72, P < 0.05), women with a history of birth-defect-affected pregnancy (OR = 32.73, P < 0.05) and women who planned their pregnancy (OR = 7.88, P < 0.10).

The rate of periconceptional folic acid use was among the lowest of those reported from other countries. More work should be done to improve preconceptional use of folic acid with special attention on less educated women and women farmers.