scientific answer: right now your ovaries are cranking out a ton of estrogen and progesterone. hcg is also present at high levels. the placenta will take over this hormone production at about 13 or 14 weeks and the nausea generally goes away then. the combination of hormones can cause the nausea in a lot of mamas. a pregnancy in hormones is the equivalent of taking 100 birth control pills a day.
acupuncture helped me, as well as using a homeopathic for nausea. the eating a cracker and getting up slow out of bed didn't work for me at all.