Interpret results with caution
Because of the significant potential for recall bias, interpret the findings of these case-control studies with caution.5 The mother of a child with a birth defect may search her memory more aggressively for potential causes than a mother of a healthy infant, leading to different rates of recalled, rather than actual, exposures. In the absence of confirmatory prospective data, such as medication diaries or pharmacy databases, recall bias accounts for many spurious positive findings in case control studies.
Recommendations from others
Food and Drug Administration. The FDA assigned guaifenesin to category C—that is, its risk cannot be ruled out. Human studies are lacking, and animal studies are either positive for fetal risk or lacking. Guaifenesin is recommended if the benefit to the pregnant woman warrants the risk to the fetus.6
ACOG. The American College of Obstetricians and Gynecologists (ACOG) makes no recommendation.7 The textbook Drugs in Pregnancy and Lactation reports that guaifenesin use during pregnancy exhibits very low risk to the fetus.6 The National Collaborating Centre for Women’s and Children’s Health suggests that guaifenesin be used sparingly during pregnancy.8