I would recommend checking with your doctor on this. I don't think an orange has enough vitamin c in it for you to be concerned. When they're talking about not taking too much vitamin c, this is for those people who tend to take thousands of milligrams at the first sign of a cold, not for those who consume it the natural way in oranges. But most likely if you are craving oranges, your body is in need of additional vitamin c and that's the reason for the craving. Just a thought ... Might be a good idea to check with your doctor.

No you do need it. Please read:

why do you need vitamin c?
Vitamin c, also known as ascorbic acid, is essential for tissue repair, wound and bone healing, and healthy skin. Vitamin c also helps your body fight infection.
Both you and your baby need this vitamin daily — it's the cementing agent that holds new cells together. It helps your baby grow and builds strong bones and teeth. And it helps your body absorb iron. Try to include a vitamin c-rich food with every meal to get the most iron out of the other foods you eat.
How much do you need?
You'll need at least 85 mg of vitamin c daily during pregnancy — about what you'd expect to get if you drink a small glass of orange juice. That goes up to 120 mg when you're breastfeeding.

Should you take a supplement?
Probably not. It's easy to get the daily requirements through food. A glass of calcium-fortified orange juice at breakfast every day is all you need.

What are the best food sources?
Citrus fruits, tomatoes, tomato juice, potatoes, brussel sprouts, cauliflower, broccoli, cabbage, and spinach are all good sources.

Hope it helps!!!