Your baby's brain starts developing almost at the moment of conception, according to the Long Island Spectrum Center website. By the time you are three weeks pregnant, the developing embryo has formed a neural groove, which is the foundation for the brain structure. By the time your baby is born, her brain will have over 100 billion neurons.

As a pregnant mother, you may spend plenty of time wondering about the growth and development of the life inside of your uterus. Your baby goes through a series of changes from the time of conception through birth. Most pregnancies last about 40 weeks. Your doctor may refer to your stage of pregnancy in terms of trimesters.

Bleeding during pregnancy sends off alarm bells, because it can be a warning sign that you're having a miscarriage. While you're right to be high alert, bleeding doesn't necessarily mean anything's wrong with your pregnancy. As many as 20 to 30 percent of pregnant women experience bleeding, according to the American Pregnancy Association, and of those women, only one-half have miscarriages. You can't necessarily stop pregnancy bleeding, but there are some things you can do to help prevent it and to avoid making it worse.

The development of a fetus into a healthy baby is a complicated and delicate process. Genetic factors can sometimes cause the baby to be born with genetic disorders. Other diseases that can affect a baby in the womb are passed to the baby when the mother suffers from them. For this reason, it is important for a pregnant woman to keep herself as healthy as possible.

Your pregnancy is a time of rapid changes for both you and your developing baby. Health professionals commonly refer to the stages of pregnancy as trimesters. Normal pregnancies last approximately 40 weeks from the time of menstruation to delivery. Each trimester includes certain developmental milestones for your baby.

There's something almost magical about feeling those first, fluttering movements of your baby in the womb. Later on, those delicate twitches can turn into painful kicks and jabs. Although so much activity might be frustrating to you -- especially late at night, when you are trying to sleep -- your baby's movements are actually very healthy and a normal part of his development.

A baby develops the ability to hear sounds at about 18 weeks into the pregnancy, according to MayoClinic.com. The uterus, though snug and warm, is not soundproof. In fact, your baby can hear -- and respond to -- a wide range of sounds, from those your body makes to sounds outside your womb.

There's an old saying that if a pregnant woman has heartburn, her baby will be born with a full head of hair. Interestingly enough, there is a correlation between heartburn and hair on a baby, according to the New York Times. Still, a baby born with hair might not keep that hair. In fact, it is hard to predict just when your baby's hair will grow, how fast it will grow or how much she will have.

A fertilized human egg is less than 0.1 mm across. A full-term baby averages a little over 19 inches in length. This remarkable growth occurs over the course of nine months. During the last four weeks of pregnancy, body growth slows as the baby puts on weight -- mostly in the form of body fat -- in preparation for birth.

The development of a baby in utero is truly remarkable. Only a few weeks pass between the time an egg is fertilized and the heart begins to beat. While the organs may grow rapidly, some are not fully functional until the baby is full-term and ready to be born. Others, such as the heart, are functional before the end of the first trimester of pregnancy.