The nine month journey of pregnancy is both mysterious and amazing. Throughout this time, your baby moves from a single cell to a fully formed human infant. The nine months of pregnancy are divided into three trimesters. The first trimester actually begins before you ever become pregnant. Your due date will be 40 weeks from the date of your last menstrual period.
The First Month:
The first month of pregnancy begins when the sperm meets the egg. Of the hundred million sperm to enter the woman’s body, only about one to two hundred reach the egg. The first to penetrate the egg’s membrane will add its DNA to form the baby. If that sperm carries an X chromosome, the baby will be a girl; a Y chromosome and the baby will be a boy. The membrane automatically becomes tough and won’t allow any others to enter.
About a week later, the tiny mass of cells that will become your baby implants in the lining of the uterus. The cells divide rapidly. The outer cells will become the placenta, which will connect you and the baby for the next nine months, providing nourishment and carrying away waste. All this happens before you have even missed a period. At the end of this month, your period won’t come and you may begin to suspect that you are pregnant.
This month is the most significant period of development for your baby. During this month, the embryo goes from a microscopic ball of cells to resembling a miniature human being. During the first week of this month, the nerves that will become the brain begin to develop. The neural tube forms this week, too. This tube will become the spinal cord.
About a week later, the tiny heart forms and begins beating. The heartbeat can be seen on an ultrasound, but can’t yet be detected by a doppler. During the next two weeks, tiny buds hat will become the arms and legs begin to sprout small ridges that will become the fingers and toes. Eyes will begin to form. By the end of this month, the baby’s major organs: the lungs, intestines, kidneys and liver are in place but are not completely formed.
The Third Month:
During the first part of this month, all the embryos internal parts are formed. The kidneys begin to secrete urine. Bones and muscles are starting to grow and the ribs and backbone form, but are not hard. The skin of the embryo is transparent and all the organs and forming bones can be seen. Also during the first half of this month, the baby’s facial features are beginning to form. A boy baby will begin to develop testicles, while a female baby will begin to develop ovaries.
The second half of this month the embryo has all the internal parts and officially becomes a fetus. The umbilical cord is formed and contains one vein to bring nourishment to the fetus and two arteries to carry away waste. By birth, the cord will be about 20-22 inches long and an inch thick. By the end of this month, the baby’s fingers and toes are no longer webbed and the fingers become more distinct. At the end of this month, your doctor will be able to detect the baby’s heartbeat with a doppler.