antibiotics

They argue there is not enough evidence to back the idea that stopping pills early encourages antibiotic resistance.

Instead, they suggest, more studies need to be done to see if stopping once feeling better can help cut antibiotic use.

But GPs urge people not to change their behaviour in the face of one study.

Prof Helen Stokes-Lampard, leader of the Royal College of General Practitioners, said an improvement in symptoms did not necessarily mean the infection had been completely eradicated.

Macrolides, quinolones, tetracyclines, sulfonamides and metronidazole were related to higher rates of pregnancy loss, the researchers say. However, a greater chance of pregnancy loss was not seen with the most frequently used antibiotics, including penicillin.

"It is reassuring to see that first-line treatments and antibiotics that are the most used in the population (penicillin, cephalosporin) were not associated with an increased risk of miscarriage," Dr. Anick Bérard, lead researcher and a member of the Faculty of Pharmacy at the Université de Montréal, wrote in an email.