Generate a query that a web user would issue to a search engine to find the following document on the internet: 

Document: We don't know a lot about the effects of caffeine during pregnancy on you and your baby. So it's best to limit the amount you get each day. If you are pregnant, limit caffeine to 200 milligrams each day. This is about the amount in 1½ 8-ounce cups of coffee or one 12-ounce cup of coffee.

Before generating the query, first explain what the document is about and then generate the query. The output format should be:
Explanation: <>
Query: <> Write your response with at least 700 words.
user