How does the baby develop over the nine months?

During the 9 months of pregnancy, there are many things that are going on. During this period, your baby develops from a fertilized egg to a blastocyst, then from an embryo to a fetus, and finally to the baby you have been eagerly waiting for!

During the first trimester, you conceive. The fertilized egg develops into a blastocyst and begins to burrow into your uterine lining. The cells of the blastocyst start developing into different groups, each group having a different mission. Some, for instance, will start forming the placenta, while others will start forming various parts of your baby.

Within 21 days, a rudimentary heart will start beating and circulating blood and the umbilical cord appears about 4 weeks after conception. And although it's only the size of a grain of rice, your baby has small buds that will eventually develop into arms and legs, a brain, a primitive spinal column, as well as rudimentary elements of future organs, from the mouth and stomach to the liver, thyroid, gallbladder and many more.

Throughout the first trimester, rapid development continues. Your baby will grow from the size of a grain of rice to nearly 5 inches long, developing from an embryo to a fetus. From an indefinite shape, the baby will start looking like a human being in miniature. By this time, your baby will be having arms, legs, fingers, toes and even nails.

Your baby also begins to grow hair and tiny tooth buds start appearing in the baby's gums. Thousands of new nerve cells are created every minute and the baby is beginning to create his own red blood cells in the spleen, liver, and the bone marrow. Almost all of your baby's organs are formed towards the end of the first trimester; and the organs continue to grow and develop during rest of your pregnancy. If you're able to observe the baby's genital area via ultrasound, you should be able to tell if your baby is a boy or a girl.

In the next month, the baby quadruples his/her weight and doubles in length. Fingerprints develop and the baby starts breathing in amniotic fluid, which helps the lungs grow and develop. At around 20 weeks, the baby's skin begins to develop a coating called the vernix. The vernix helps protect the baby's skin from the amniotic fluid. You're probably starting to feel your baby move at this point, and as the structures of middle ear continue their development, the baby begins to hear you. As the second trimester draws to an end, your baby will be nearly 12 inches long and weigh about 1.25 to 1.5 pounds.

As you move into the third trimester, the baby starts to open his eyes. His senses of smelling, hearing, and tasting are well developed. The baby starts to respond to both sound and touch. By 34 weeks, he'll blink his eyes in response to any bright light. Till now, your baby has perhaps been in a bottom down or breech position, but around 34 weeks, most of the babies change to a head down position. They stay in this head down position until birth. The most important development during this time is secretion of surfactant in baby's lungs which is essential for breathing outside the womb.

From this point forward, the baby gains about one-half pound each week and even you'll gain about one pound each week. By 38 weeks, the baby will weigh anywhere between 6 to 7.5 pounds and will be between 18 to 20 inches long.

The baby will also have certain waking and sleeping patterns, similar to those of a newborn. Around this time, your baby's lung will have enough surfactant so that he/she is able to breathe on its own once born. Your baby will spend the last few weeks of pregnancy practicing for life outside the womb - breathing, moving, grasping, sucking, swallowing, and sleeping in preparation for the new life!