Little information is available about the safety of high doses of mesalazine during pregnancy.


To study the fate of pregnancy and foetal outcome in women taking 1–4 g/day of mesalazine microgranules for inflammatory bowel disease.

Patients and methods:

Case reports were collected from the Pharmacovigilance Department of Ferring SA, France, from a survey conducted in three gastroenterology units, and from a teratology information service. The evolution of pregnancy and foetal outcome were assessed by questionnaire.


The study covered a total of 123 pregnancies (126 foetuses). Ninety-six women took mesalazine during the first trimester, 85 during the second and 83 during the third. The mean daily dose was 2.1 ± 0.8 g; 86 women received <3 g/day (low-dose group), 37 women received ≥3 g/day (high-dose group). The following abnormalities were observed in the low-dose and high-dose groups, respectively: ectopic pregnancy (1/0), spontaneous abortions (1/1), foetal death (0/1), premature deliveries (3/5, < 0.05), congenital malformations (3/1) and one case of lethal oxalosis. Abnormalities were not considered to be related to mesalazine.


The use of oral mesalazine microgranules during pregnancy is safe at doses ≤ 2 g/day, and probably also at a dose of 3 g/day.