PREGNANCY STAGES
Pregnancy lasts for 40 weeks, beginning from the first day of a womans last menstrual period. The most common method used to determine whether a baby is developing at the proper rate is a 28-day. Though its a little difficult to understand, a woman has already been pregnant for two weeks at the time of what is considered conception because the sperm and egg join two weeks after the first day of a womans last period.
During the nine months of pregnancy, most babies generally develop at the same rate. This is often known as fetal development, and a womans estimated due date or the date the baby is expected to be full-term and ready to be delivered is set at exactly 40 weeks. A baby born prior to the 37th week is considered premature and could have many health issues that need to be addressed medically at the time of birth.
The first trimester
The first trimester is considered as the first one-third of pregnancy, or week 1 through week 13. In the beginning, there are so many amazing things happening in the mothers body that it is hard not to notice or feel a physical difference. The baby commonly called an embryo at this stage of pregnancy begins to form from a single fertilized egg during the second week, dividing into two cells, then four, then eight, and so on. The embryo floats from the fallopian tube down into the uterus, where it implants itself. During the third week, the developing embryo is only one-hundredth of an inch long, but it is rapidly multiplying cells until the fourth week, where a woman may miss her monthly period and first begin to suspect that she may be pregnant.
It is during the fourth week that the embryos cells begin to take on specific functions; the backbone, spinal column, and nervous system are forming. At five weeks the embryo is only the size of a raisin, and the tiny heart begins to beat and the main external features start to form. During the sixth week, the kidneys, liver, and most organs have already started to develop and arm and leg buds become visible. Fingers start to take shape at during week seven, and at eight weeks the unborn baby is considered a fetus and is about half-an-inch long. The fetus heart is nearly completely developed at ten weeks, with vital organs almost fully formed at eleven weeks.
Second trimester
Weeks 13 through 26 are the second trimester; it is during this time that most nausea or morning sickness subsides, fatigue lessens, sleeping comes easier, and pregnant women generally have an overall happier three months. During the second trimester, or fourth, fifth and sixth months, the babys fingerprints are in place, facial features start to resemble those of an adult, taste buds form, and it can taste its mothers meals. A pregnant woman can begin to feel the baby kick or move for the first around week 16. Its between week 18 and week 21 that starts to show the babys gender. A child can hear and recognize its mothers voice around 20 weeks, which is an important time for sensory development like smelling, tasting, seeing, hearing, and touching. And although it is tiny and fragile, weighing less than a pound, a baby born at 20 weeks could possibly live with medical intervention.
The baby begins to fatten up during week 21, gaining fat steadily in order to stay warm and maintain his or her body temperature. By week 23, the fetus is exactly proportionate to a newborn except that he or she is a thinner version since it hasnt gained enough body fat yet. Baby can practice breathing some more during the 25th week, when it weighs over 1-1/4 pounds. Its brain is growing at a rapid speed and the baby is also growing swiftly, filling the space inside the mothers uterus. During week 26, a baby makes breathing movements without air in its lungs, and a fetal brain scan will show a response to touch.
Third trimester
Week 27 begins the third trimester, when a fetus does most of its growing. During these last three months, babys eyes begin to open, it can suck its thumb, its brain and head grows bigger, its ears start to increasingly hear sounds, and its lungs and kidneys mature. By week 38, a pregnancy is full-term and babies weigh an average of 7.5 pounds and are 18 to 20 inches long.
