Cantaloupes appear to be a healthy fruit, however, they have been associated with potentially deadly salmonella and listeria outbreak. Listeria is especially deadly during pregnancy, and can potentially lead to a miscarriage or stillbirth.

This makes the cantaloupe one of the few fruits associated with potentially worrisome infections. "If in doubt, don't eat it."  

Read More:
(Pre) Pregnancy Nutrition and Food Guide
Foods to Avoid During Pregnancy
Pregnancy Safety Guide