The rapid pace of growth that is inherent in the embryonic stage continues at an astronomical pace. In fact, during these early weeks of quick growth your baby is adding more than a million new cells each minute. The early brain of your developing baby is now divided into three main sections; the forebrain, which becomes the eyes and the nose; the midbrain and the hindbrain. Kidneys are now forming, as well as the digestive tract.

The circulatory and respiratory systems also begin taking shape during this week. The beginning respiratory tract extends to become two full breathing passages, the bronchi. The heart now develops four full chambers, and already the baby's heartbeat may be visible by ultrasound, even though you won't be able to hear it yet.

If you visit a health care provider for your pregnancy test, they will be able to observe "Goodell's sign" during a pelvic examination. Goodell's sign is the softening of the cervical tip.

The same hormones that cause softening of the cervix, are the hormones that cause morning sickness. By this point you've probably noticed breast tenderness, fatigue, nausea or other signs of pregnancy.

By the end of the fifth week your baby has more than doubled in size and is one centimeter long. Every major organ has already begun to develop. Your doctor or midwife will likely encourage you to take prenatal vitamins and begin using a healthy pregnancy diet to ensure your nutrient intake is good enough to support the baby's growth.

Did you enjoy this article? It is part of the Pregnancy - Week by Week Through the First Trimester ebook available today!

Resources:
The Pregnancy Book: Month-by-Month by Dr. Sears

Your Pregnancy Week by Week by Lesley Regan

The Complete Book of Pregnancy and Childbirth by Sheila Kitzinger