The American College of Obstetrics and Gynecology Obstetric Practice Committee has issued recommendations on the use of sulphonamides and nitrofurantoin during pregnancy. This follows a paper published in 2009 that found both categories to be associated with an increased risk of birth defects.
 

The Committee assessed the study, and also other available evidence, and concluded that the 2009 study had significant limitations including a risk of recall bias. Other studies have not shown any such association. Based on the 2009 study and other evidence, it concluded that commonly used antibiotics, such as the beta-lactams and macrolides, and also the less commonly used quinolones, were not associated with any significant increase in risk of malformations.
 

Overall, the Committee advises that antibiotics should be used during the first trimester only when appropriate and for the shortest necessary period. Prescribing sulphonamides or nitrofurantoin in the first trimester is still considered appropriate when no other suitable alternative antibiotics are available. During the second and third trimesters, these drugs may continue to be used as first-line agents for the treatment and prevention of urinary tract infections and other infections caused by susceptible organisms. They also comment that pregnant women should not be denied appropriate treatment for infections because untreated infections can commonly lead to serious maternal and foetal complications.