Directly from the Carnival Web Site:
http://www.carnival.com/CMS/Static_Templates/EMB_minor_pregnancy_policy.aspx
PREGNANCY POLICY Pregnant women are only allowed to sail if pregnant for 24 completed weeks or less at time of cruise disembarkation. All pregnant women are required to produce a physician’s letter stating that mother and baby are in good health, fit to travel and the pregnancy is not high-risk. The letter must also include the estimated date of delivery (EDD).
Not sure how you consider that deceptive in their policy. Since they have this policy any dispute with your credit card is not going to go anywhere. So if it does go to court you will probably loose. You will then not only owe the original amount, but the additional interest, fees, and court costs that were accrued. You may want to use your time and energy with Carnival to see if they can do anything for you. Keep in mind that every other Cruise line has very similar policies in regards to Pregnancy.