At the end of the 80's several studies have suggested a potential increased risk of neural tube defects (NTDs) with ovulation induction/fertility drugs, especially with clomiphene citrate (CC). A previous meta-analysis of observational studies evaluating the risk of NTDs associated with the use of CC performed in 1995 found a risk ratio of 1.08 (95% confidence intervals (CI) 0.76-1.51). Since then, additional studies have been published and the risk of NTDs associated with periconceptional CC exposure may have changed.