The First Trimester Of Pregnancy

Changes in the woman's body and development of the fetus during the first trimester (three months) of pregnancy.

There is little doubt many changes occur to a woman's body during the first trimester of a pregnancy. The pregnancy itself is dated from the last menstrual cycle of the woman with conception occurring sometime around the fourteenth day.

During this time an ova has been released from the woman's ovaries and if fertilized by a man's sperm somewhere in the fallopian tubes. Once a sperm has been able to pierce the ovum's protective covering, a chemical reaction takes place so no other sperm can reach the center of the ova.

The fertilized egg will continue down the tube into the uterus multiplying at phenomenal rates. At first dividing within hours to a two-cell zygote it continues for four days and becomes a blastocyst, consisting of about one hundred cells.

By this time the blastocyst has implanted itself into the endometrium or lining of the uterus and the woman in considered officially pregnant. Once the blastocyst has become implanted, substances are secreted which cause changes in the woman's body that usually include a halting of the normal menstrual cycle. This halting is first sign a woman has that she may be pregnant.

As the blastocyst becomes an embryo, the woman is usually starting to suspect she may be pregnant. As the time for her period has come and gone, a woman may be feeling some nausea as well as a tender, lumpy feeling to the breasts. A home pregnancy test will check the woman's urine for traces of the pregnancy hormone, human Chorionic Gonadotropin (hCG) that starts being produced approximately one week after conception.

Another common sign of pregnancy is the need to urinate small amounts with greater frequency. Women during this first month will also suffer from fatigue. This has been attributed to the sedative affect high levels of the hormone progesterone have.

The embryo is now a becoming visible to the naked eye. When looked at, it has a distinct top and bottom with a stripe down the back that curling over to form a groove. This groove will eventually close up forming a tube in which the spinal cord and brain will develop. There is already a bulge in the center of the embryo where the heart will be formed and the beginnings of a rudimentary vascular system in place.

During the sixth week, symptoms may hit in full force. Morning sickness may occur on a regular basis every morning or even stick around the entire day. In severe cases, vomiting may become a problem the doctor may want to address if it interferes with a woman's ability to keep any food down or she is losing a substantial amount of weight. Fatigue sets in and stays while hormonal levels often cause moodiness and irritability. It is important at this stage for the woman to listen to her body and rest as much as possible.

The embryo at this time has developed the spinal tube and her brain is growing to fill the head. Dark areas can be seen on either side of the head. These are optic vesicles and will eventually give the baby its sight. The heart may start to beat this week and tiny limb buds emerge. These buds will form into the arms and legs later on. At this time its overall length from rump to crown is approximately 0.08-0.16 inches.

By the seventh week, the cervix has started to soften and the mucus plug at the cervical canal is formed. This "plug" seals off the uterus from the outside world and will remain in place until shortly before labor.

A woman usually gains little weight during the first trimester. Most doctors recommend an overall pregnancy gain of 20 - 30 pounds and the common gain during the first trimester is only 2-5 pounds.

This week has shown great progress in the embryo. Its digestive tract is beginning to form with a hindgut already present. The "tail" will start to fade while the lungs have begun developing as well. The placenta has formed and the umbilical cord starts growing to transport nutrients to the embryo while removing toxins. A face has started to appear with slight coloring to the iris of the eyes and perforation has begun for the mouth. Tiny nostrils have appeared and the limb buds now show distinct areas of hand and shoulder placements.



During the eighth week, a woman often can tell the uterus is growing because her waistbands are becoming tight. The unpleasant feelings of tiredness and nausea continue during this week as the body tries to adjust itself to the pregnancy.

The embryo on the other hand now has tiny fingers and toes forming as well as showing bends at the elbows, wrists and knees. Its ears are starting to form while the upper lip and nose have begun to develop, as have eyelids. Overall length has gone to 0.5 to 0.8 inches and weight has climbed to about 0.1 ounce.

The ninth week can often bring an onset of pimples while at the same time the skin of the face appears softer, smoother and "blooming". This is the glow often heard of that women get while pregnant. The HCG hormone reaching its peak levels causes it. The breasts not only can seem fuller, they become much more tender as well. This is due to the mammary glands getting ready for milk production. Women will also often have a clear vaginal discharge as well. This discharge can usually be ignored as long as it remains color and odorless.

The embryo's head at this time is still much larger than the rest of its body and is usually curved down towards its chest. The back is starting to straighten out; the eyes have become well developed but are usually covered by the lid. Fingers are separating into individuals and muscles have started to develop allowing for tiny movements. From rump to crown the embryo is between 0.9 and 1.2 inches with a weight of approximately 0.12 ounces.

Week ten finds the woman often getting strange mood swings that can include crying jags, depression, sudden anger and flights of feeling on top of the world. Her body has started to put on more weight and there is often a softening of the gum tissue. It is highly recommended she take special care of dental hygiene from this point on.

The tenth week will usually see the embryo's body plan laid out. By the end of this week he or she is out of the risk period for developing congenital abnormalities. If male, the testes will already be producing testosterone, the heart is completely developed, the brain is growing at a rate of a quarter of a million neurons every minute and the buds for taste and teeth have started to develop as well. Measuring between 1.25 and 1.68 inches, it will weigh around 0.18 ounces.

A woman's basal metabolic rate has often increased by 25 percent by the eleventh week of pregnancy. The amount of blood that is flowing through her body has also increased and she will often perspire more and feel warm regardless of the temperature around her. Skin pigmentation is often darkened in areas such as in the areola around her nipples. Genitals may also darken and freckles often become darker while a line starting at the navel and traveling down may appear. This line is called the linea nigra and shows where the muscles are being affected by the growing of the uterus. In most cases, these changes in skin pigmentation will fade within the weeks following the birth of the baby.

During week eleven, the embryo is now called a fetus and will grow at an awesome rate until week twenty.

The placenta has also grown in size and its number of vessels has increased to accommodate the changes in the fetus. The head of the fetus accounts for about half the overall body length, which has grown to be between 1.75 and 2.4 inches long.

Doctors will often order ultrasounds during week twelve. This will allow for a more accurate estimated due date by measuring the fetus from crown to rump. The uterus itself has become too large to continue sitting down in the pelvis and it will start to move up into the abdomen. The blood volume has continued to increase and the heart rate will start to rise a few beats a minute to be ale to circulate it all through the body.

Women will usually start feeling better by this time with the incidence of nausea decreasing or actually disappearing. Energy levels will become more balanced and if an ultrasound is done, the idea of an actual baby being in the uterus often hits the mother full force with her first sighting of her baby.

The fetus has continued to grow at a phenomenal rate, often having doubled its size in just the last three weeks. The muscles are developed enough to allow spontaneous movements although the fetus itself has no voluntary control. The face looks much more human, the finger and toenails have started to develop and all the intestines are in the abdomen. If male, the developing genitalia are well on its way. The chances of miscarriage have greatly diminished and soon the fetus will be making his or her presence know by movements strong enough for the mother to feel.

The first trimester is the most important for the developing baby. All of the major systems and organs of the body have been developed and from this point on are only growing and being enhanced. Women should remember to eat adequate diets with high levels of folic acid and other nutrients necessary for the formation and well being of the baby. She should also consult her doctor about ANY medications, prescription or over the counter before taking them and always inform medical personnel of her condition before having any type of x-rays done. Simple, common sense precautions will give the baby the best chance for normal development he or she can have and isn't this something they all deserve?

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