First Trimester 0 to 12 weeks

By six weeks your baby is the size of a pea. By seven to eight weeks all the baby's major organs are partly formed. Your body creates two special organs to support and nourish your child. The amniotic sac surrounds the baby with fluid and acts like a shock absorber. The placenta is your baby's life support system. It feeds your baby, brings oxygen and gets rid of wastes through the blood. Anything you eat, drink, or smoke, including drugs, will be delivered to your baby through the placenta. Good nutrition is required so that your body has the right building blocks for a healthy pregnancy.

Second Trimester 13 to 28 weeks

During this trimester your baby starts to hear and may startle at loud noises. Sex organs are maturing. Hair grows on your baby's head. He or she can cough or hiccup. Your baby is very active. You need to drink plenty of fluids and eat sensibly to help your body support your growing baby.

Third Trimester 29 to 40 weeks

Your baby does most of his or her maturing now. By six months your baby weighs less than one kilogram (less than two lbs). At birth the average baby will weigh between two and a half to four kilograms (six to nine lbs). Brain cells are growing very fast. Calcium is especially needed now for proper bone and tooth growth. Your baby is getting ready to be born.