As nice as it would be, nature doesn't include an abdominal window so you can see your baby's sex before birth.

One of the most reassuring sounds a pregnant mother can hear is the steady thumping of her baby's heartbeat. Before 20 weeks of pregnancy, fetal heartbeats are typically monitored by doctors using a heart rate Doppler. While buying or renting an at-home Doppler is possible, it is often too expensive.

The use of fetal monitors to monitor fetal rate began at Yale University in 1958. Today, most hospitals use fetal monitoring as a standard component of the labor and delivery process. Fetal monitoring can provide valuable information, such as detecting dips in your baby’s heart rate due to lack of oxygen.

With so much focus on body care and post-delivery parenting, the effect of maternal stress on an unborn baby is still a topic in need of more research and attention.

A fetus passes through seven stages of development during the 42 weeks of a pregnancy. During those 42 weeks, the mother experiences the development, too, as her body changes. Many permanent features form during the first two weeks of the baby’s development after conception.

Knowing how to determine your unborn baby's position can be quite valuable as you progress and grow closer to your delivery date. "The Mayo Clinic Guide to a Healthy Pregnancy" says that in the final weeks, most babies will be positioned head-down, with their faces angled toward your spine.

Exposure to harmful substances in the earliest weeks of pregnancy -- often before a woman realizes she's pregnant -- can pose risks to human embryos.

The kidneys start to grow during the first month of fetal development. These organs produce urine and maintain normal levels of electrolytes and fluids in the body. Kidney problems that occur during fetal development could lead to complications after birth.

Lung development in a fetus starts during the embryonic phase, at around four weeks of gestational age. Very early in development, what will eventually be a baby is nothing more than a cell ball, where none of the cells are yet specialized.

Barbiturates such as phenobarbital are used to treat epilepsy. These medications are a type of depressant and act on the brain to inhibit the misfiring of the brain in epilepsy. Barbiturates are also a common drug of abuse. Women who abuse barbiturates can experience memory loss, irritability and changes in alertness.

Normally, pregnant women stop having menstrual periods, but vaginal bleeding may still occur during pregnancy. Although the bleeding can be worrisome, it is most common for women during the first trimester, the first 12 weeks of pregnancy.