In the first trimester, hormone changes can cause nausea and vomiting. This is called "morning sickness," although it can occur at any time of day. Morning sickness usually tapers off by the second trimester. 

What might help: 
•    Eat several small meals instead of three large meals to keep your stomach from being empty. 
•    Don't lie down after meals. 
•    Eat dry toast, saltines, or dry cereals before getting out of bed in the morning. 
•    Eat bland foods that are low in fat and easy to digest, such as cereal, rice, and bananas. 
•    Sip on water, weak tea, or clear soft drinks. Or eat ice chips. 
•    Avoid smells that upset your stomach. 
Call your doctor if you have flu-like symptoms, which may signal a more serious condition. 
Call your doctor if you have severe, constant nausea and/or vomiting several times every day.