The first few months of pregnancy — the first trimester — are marked by rapid changes.

During the first trimester, physical changes may include breast tenderness, fatigue and nausea. Emotions might range from excitement to anxiety. For the fetus, the first trimester is a time of rapid growth and development. The brain, spinal cord and other organs are forming. The heart begins to beat. Fingers and toes begin to take shape.

When you find out you're pregnant, make an appointment with your health care provider to begin prenatal care. You'll learn what to expect during the first trimester and beyond.