Maternal Cyclobenzaprine Exposure and Risk of Birth Defects in the National Birth Defects Prevention Study (1997-2011) and Birth Defects Study to Evaluate Pregnancy Exposures (2014-2018).

Even in our large sample, cyclobenzaprine use was rare. Our estimates are unadjusted and imprecise so should be interpreted cautiously. These hypothesis-generating results warrant confirmation and further research to explore possible mechanisms.