Background The use of drugs during pregnancy is always controversial. There is limited information about the use of infliximab during pregnancy.

Purpose To describe the effectiveness and safety of infliximab in a patient with ankylosing spondylitis during pregnancy.

Material and methods Retrospective and observational study of a pregnant woman with ankylosing spondylitis who was treated with infliximab.

The data collected was: week of gestation, infliximab dosage and laboratory data: erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP).

Results A 32-year-old woman was diagnosed with ankylosing spondylitis in 2005 and she started treatment with infliximab 5 mg/kg every 8 weeks in 2007. In 2012, she got pregnant and stopped treatment (CRP < 0.3 mg/dL and ESR = 2 mm/h).

Due to this treatment interruption, she started suffering diffuse polyarthralgia, soreness and disabling pain. At week 14 of pregnancy, her ankylosing spondylitis flared up with pain in several joints. She was prescribed corticosteroids without success and she asked to resume treatment with infliximab.

The teratogens centre indicated that there was no absolute contraindication. Therefore, the hospital’s Medical Director authorised the off-label use of infliximab in a pregnant woman.

At week 16 of pregnancy, she was treated with infliximab (previous values: CRP = 1.1 mg/dL and ESR = 40 mm/h). After that, she showed a significant improvement (ESR = 9mm/h).

She was retreated at weeks 23 and 30 of pregnancy (values after the second dosage during pregnancy: CRP = 0.4 mg/dL and ESR = 2 mm/h).

At week 40 of pregnancy, she gave birth without any problems. The newborn weight was 3.420 kg and the APGAR score was 9/10.

She restarted the treatment with infliximab two weeks after birth, the previous values were CRP = 7.4 mg/dL and ESR = 33 mm/h, but they quickly normalised (CRP < 0.4 mg/dL and ESR = 6 mm/h).

Conclusion In our limited clinical experience, infliximab was safe and effective in our patient. However, the use of infliximab during pregnancy should be studied on a case-by-case basis.

References and/or Acknowledgements We thank the entire department for supporting this work.

No conflict of interest.