Special considerations are needed when using local anaesthesia during pregnancy and the postpartum period, especially during lactation. The use of local anaesthesia during pregnancy is considered safe, however, the benefits and risks for the mother and fetus must always be considered.
The FDA has a drug classification system based on the risks to pregnant women and their fetuses. Of the five categories (A, B, C, D, and X) lidocaine is considered in Category B, the safest of the local anaesthetics. Mepivicaine and bupivacaine are Category C and may be used with caution.
During the first trimester and during lactation local anaesthesia without vasoconstrictor should be considered to avoid possible idiosyncratic reaction to the fetus and neonate, not to the vasoconstrictor but to the preservative used to stabilize the vasoconstrictor. Prilocaine should not be used due to the risk of the fetus developing methemoglobinemia. In the second and third trimesters, proper positioning and heart rate monitoring are important to avoid postural hypotension.6