Stages of Pregnancy Development week by week

First Trimester – Week 1 through 12:
According to this method, the beginning of pregnancy is measured beginning on the first day of your menstrual cycle, thus before conception. It may seem strange that stages of pregnancy start before there’s a baby growing, but think of it as the oven preheating before putting the bun in to bake. If a woman wants to become pregnant, now is the time to start healthy habits that will help her baby throughout the rest of the pregnancy. Eat right, exercise and rest well. Drink plenty of water and stop any bad habits like smoking and drinking.

From week 21 to 24 eyebrows and eyelids come into place. If you were to stretch out his little legs, your baby would be about 10 inches long. At the end of the 2nd trimester, your little guy starts to put on baby fat as his wrinkly skin smoothes out.
3rd Trimester – Week 28 to 40: By the 3rd trimester, some amazing transformations have taken place. Your baby will weigh about 3 pounds and is more than 15 inches long! Also, he can open and close his eyes and follow a light. By eight months, your baby is gaining more fat and his lungs are well developed. He will weigh about 4 ¾ pounds by the end of week 37. During the last 4 weeks, babies end up varying a great deal in size, just as adult people do. The average size of a baby about to be born is more than 19 inches long and nearly 7 pounds. The head usually will be pointing down, and if the baby is breech (feet down) or transverse (laying across) in the uterus, your doctor may consider a c-section.

Hopefully this week by week pregnancy guide, even though it's not an exact pregnancy calender, will help explain a little bit about what's going on inside your body. However, all pregnancy information should be checked with your doctor or midwife.