|
|
Congratulations! You are about to embark on a magical journey during which your body will change dramatically in order to nurture and develop the growing life within you. A microscopic egg and its fertilizing sperm develop in a predictable way to produce what will be your new baby in just nine short months.
Let’s review the highlights of fetal growth and development. Pregnancy is divided into thirds, or trimesters, each lasting about twelve to thirteen weeks. Obstetrical care providers calculate your progress in pregnancy in weeks (instead of months) beginning with the first day of your last menstrual period. Pregnancy lasts on average forty weeks or 280 days. For the first eight weeks after fertilization, or ten weeks after the first day of your last menstrual period, your developing baby is called an embryo. During this period, all the major organs are formed, but are incompletely developed. After the embryonic period, your baby is called a fetus. While the division into trimesters is somewhat arbitrary, it has some important implications.
For example, the embryo is most vulnerable to environmental toxins during the first trimester; this is the period during which miscarriages most often occur. On the other hand, babies who are born prematurely, but reach the third trimester, have a greater chance of survival.
In the first six weeks of pregnancy, dramatic changes occur in the developing embryo. Tiny limb buds appear, which grow into arms and legs. The heart and lungs begin to form, and by the end of this period, the heart starts to beat. The neural tube, destined to become the brain and spinal cord, is forming. By six weeks gestation, your baby is about a half inch long and weighs less than an ounce.
In the following month, or weeks 7-10 menstrual age, the tiny placenta begins working. Ears, eyelids, fingers, and toes are developed. The neural tube closes. By the end of this period, your baby looks more like a person and is about the size of a cashew.
The ribs and backbone are very soft and the skin is almost transparent. The internal reproductive organs are developing, but the gender is not yet apparent externally. By the end of the third month after conception, the fetus reaches four inches in length and just over an ounce in weight. At this time, your baby’s heartbeat can be heard with a Doppler device in the doctor’s office.
The second trimester is a time of continued maturation and growth of the fetal organs. In the fourth month, a fetus kicks, swallows, and can hear her mother’s voice. The external genitalia become recognizable. By the end of the fourth month, the fetus is still only six to seven inches long. During the fifth month, the fetus is more active, and fetal movement becomes perceptible. This is an ideal time to have an ultrasound to examine the baby’s anatomy. By the end of the fifth month, the fetus is eight to twelve inches long and weighs about five ounces. After six months, the fetus is already eleven to fourteen inches long and weighs one to one-and-a-half pounds.
During the third trimester of pregnancy, fetal growth and maturation continue in preparation for life outside the uterus. Developmental milestones include the ability to open and close the eyes, suck the thumb, respond to lightand sound, and cry. Stretching and kicking continue. By the end of the seventh month, the fetus is fifteen inches long and weighs about three pounds. After 34 to 35 weeks, the baby gains about one-half pound per week. Most babies by this time are turned “head down” inside the uterus. By 37 completed weeks, the baby is considered full term, mature, and ready to breathe and function after delivery. By 38 to 40 weeks, the baby weighs six to nine pounds and is 19 to 21 inches in length.
It is never too early, even before you suspect that you are pregnant, to begin to practice good health habits that not only protect your health but your baby’s as well. Eat a balanced diet that includes a variety of foods from each level of the food pyramid. A daily vitamin that contains 0.4 mg of the B vitamin folic acid is recommended for all women who are planning a pregnancy. Folic acid should be continued through the first trimester and beyond. Be sure to get plenty of rest. Pregnancy should not be a state of confinement; you may continue to engage in the same recreational physical activities you participated in prior to your pregnancy.
Don’t take medications that are not prescribed by your doctor, and be sure to check with him/her before using any non-prescription preparations. This includes extra vitamins, herbal preparations, and topical medicinal creams. If you regularly take medications for a specific condition, be sure to discuss it with your doctor. If you currently smoke cigarettes, this would be an excellent time to stop. If you need help, ask your doctor. Alcohol and recreational drugs can harm a developing fetus and should not be used during pregnancy.
Knowing how your baby grows and develops makes
one marvel at the transformation that occurs over only nine months. It’s
no wonder that you are so tired!
