How a Baby Develops in the Womb
To have a baby, a couple must first conceive, which means a sperm unites with an egg and fertilizes it. This fertilized egg will travel through a woman’s fallopian tubes and rest in her uterus.
Once there, the egg will embed itself into the uterine wall and develop into a baby over the course of nine months.
During the first trimester of pregnancy, many important facts are complete. Everything from the baby’s sex to the genetic background is already decided. In addition, this is usually the time in which the mother can detect a pregnancy with a home pregnancy test.
The basic building blocks such as the placenta, blood vessels, heart, lungs, liver and stomach also begin to form. About eight weeks into the pregnancy, the baby is approximately one to two inches in size.
Arms, legs, fingers and toes form and become more distinct. Later in this trimester, the baby will double in size, with its head carrying most of the weight, and even begin to move on its own. Sexual organs will also form and doctors can use a special device to detect the sound of the baby’s heartbeat.
As the baby continues to grow and develop within the second trimester, all vital organs have formed and a variety of other significant changes will take place. For instance, the mother will begin to feel slight movements from the baby and things like fingerprints, eyebrows, lashes and nails become visible.
The baby is also beginning to look more like a newborn as the skin thickens and fat cells form. Also, the baby has developed sleep patterns that will become noticeable to the mother. Furthermore, if for some reason the baby had to be born during the second trimester, hospitals have the technology to keep the baby alive without dependence on the mother.
The third and final trimester is when the baby is at its largest, weighing approximately 6 to 10 lbs. and measuring about 19 to 21 inches toward the end of the trimester. The baby begins to gain weight at a fast pace and maintains a large amount of body fat. Bones, although soft, are completely developed at this time.
The lungs and brain are almost fully developed, plus the baby can open its eyes. To prepare for birth, the baby moves downward, head first, into the mother’s pelvic area. As a result, the mother will not feel the baby move as much since there is so little room.
After 37 weeks in the womb, babies are deemed full term and delivery can happen at any time.