Your growing baby is attaching to the lining of your womb, or uterus. This is called implantation pain and it’s a sign of pregnancy progress.
You might have a few slight cramps about 4 weeks into your pregnancy -- around the time when you’d get your period. If you aren't sure whether you're a mom-to-be, it's a good idea to take a pregnancy test. If you're pregnant, you might start to feel queasy around the fifth or sixth week.