Sarah,
Thanks for your question.
Cymbalta is currently rated Category C by the FDA for use in pregnancy. The FDA assigns a category (A, B, C, D or X) to each drug based on its known level of safety in pregnancy. Category C means that either A, the drug has not been studied in human pregnancy, or B, it has been shown to have negative effects in animal pregnancy studies. However, Category C drugs may still be used in pregnant women if the doctor determines that the benefits to the mother outweigh the risks to the unborn baby.
The risk during breastfeeding is unknown at this time, because no studies have been performed. Cymbalta can pass into the breast milk, but the effects on the child are unknown at this time. You can find more information about Cymbalta (duloxetine) here.
Best of luck,
Casey