The second trimester is, for many women, the easiest three months of pregnancy. Take the time now, while you're feeling better and your energy is up, to start planning for your baby's arrival. During the second trimester, your baby is growing quickly. Between your 18th and 22nd week of pregnancy you'll have an ultrasound so your doctor can see how your baby is progressing. You also can learn the sex of your baby, unless you'd rather be surprised.