text: Pregnancy and breast feeding Its use during pregnancy is contraindicated, although it has been placed in Australian pregnancy category C. Its use during the first trimester (during organogenesis) and 12 weeks prior to pregnancy has been associated with an increased risk of congenital malformations, especially malformations associated with maternal folic acid deficiency (which is most likely related to the mechanism of action of co-trimoxazole) such as neural tube defects such as spina bifida, cardiovascular malformations (e.g. Ebstein's anomaly), urinary tract defects, oral clefts, and club foot in epidemiological studies. Its use later on during pregnancy also increases the risk of preterm labour (odds ratio: 1.51) and low birth weight (odds ratio: 1.67). Animal studies have yielded similarly discouraging results.
  It appears to be safe for use during breastfeeding as long as the baby is healthy.
  Babies
  Its use in those less than 2 months of age is not recommended due to the risk of adverse side effects.
  Adverse effects
  Common side effects include nausea, vomiting, rash, and diarrhea. Severe allergic reactions and Clostridium difficile infection may occasionally occur. Its use in pregnancy is not recommended. It appears to be safe for use during breastfeeding as long as the baby is healthy.
  Contraindications
  Contraindications include the following:
  Known hypersensitivity to trimethoprim, sulphonamides or any other ingredients in the formulations
  Pregnancy
  Severe liver failure, marked liver parenchymal damage, or jaundice.