EXPOSURE TO BOTULINUM TOXIN IN PREGNANCY

Botulinum toxin is produced by the bacterium Clostridium botulinum and is the cause of botulism, a potentially severe illness that can lead to paralysis and acute respiratory failure. Botulism may follow ingestion of food contaminated with botulinum toxin, from toxin production by C. botulinum present in the intestine or in wounds, or from inhalation of aerosolised toxin.

Botulinum toxin type A (BTX-A) is licensed for the treatment of blepharospasm, hemifacial spasm, idiopathic cervical dystonia, focal spasticity, bladder dysfunction, the prophylaxis of headaches in adults with severe migraine, and also in the management of severe axial hyperhidrosis. BTX-A is also used in aesthetic dermatology to temporarily improve the appearance of facial lines. Botulinum toxin type B (BTX-B) is licensed for the treatment of cervical dystonia.

There are limited data on which to base an assessment of the safety of exposure to botulinum toxin (either BTX-A or BTX-B) in human pregnancy. Animal studies of exposure to botulinum toxin type A have demonstrated teratogenic risk, however available data from human pregnancies exposed to Clostridium botulinum infection or to botulinum toxin type A do not suggest a significantly increased risk of congenital malformations or spontaneous abortion, although data are too limited to exclude any increase in risk. There are no data available on exposure to botulinum toxin type B on which to base an assessment of the risks following exposure in human pregnancy.

If botulism is suspected, due to the potential severity of the illness, treatment during pregnancy should be the same as for the non-pregnant patient. Data regarding maternal treatment with botulinum antitoxin are very limited but have not shown evidence of fetal harm, and where clinically indicated treatment with the antidote should not be withheld on account of pregnancy. Additional fetal monitoring may be warranted in cases of maternal botulism, particularly if exposure is associated with maternal hypoxia. Discussion with UKTIS is recommended in all cases.

Therapeutic use of botulinum toxin type A or B during pregnancy should be reserved for appropriate indications where no suitable alternative for treatment is available. The use of botulinum toxin for cosmetic indications during pregnancy should be avoided. Inadvertent exposure to botulinum toxin type A or B would not usually be regarded as medical grounds for any additional fetal monitoring. However, other risk factors may be present in individual cases which may independently increase the risk of adverse pregnancy outcome. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments.