Below, we take a more in-depth look at hCG levels, how they're measured, and what they can mean throughout your pregnancy. We also provide a handy hCG levels chart for parents-to-be.

In general, morning sickness starts in the first trimester, around week 5, and peaks by week 9 or 10, when levels of the pregnancy hormone human chorionic gonadotropin (hCG) are highest.