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| Home > Reproductive Anatomy > Pregnancy Calendar > The Third Trimester
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| | The Third Trimester in Preganancy
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You`re down to the final trimester. But you can hardly wait to hold your baby and to wear regular clothes again. It is during this period that the fetus reaches viability, and may survive if born prematurely, although their chances for both survival and easier transition to independent life improve as they near their due date.
The 28th week to 38th week of Pregnancy
Fetus
 Your baby is still growing and moving, but now it has less room in your uterus. Because of this, you might not feel the kicks and movements as much as you did in the second trimester. You may feel arm and leg movements rather than whole body shifts. If you feel a series of rhythmic jolts, your baby probably has the hiccups. Your baby may start sucking his thumb while still in the womb. During this final stage of your pregnancy, your baby is continuing to grow. The fetus gains about three and a half pounds and grows about five and a half inches during this part of your pregnancy. Even before your baby is born it will be able to open and close its eyes and might even suck its thumb.
The third trimester is the "finishing period" for the fetus. In the final stages of pregnancy, antibodies from your body pass through the placenta to give the baby short-term immunity against diseases to which you are immune. That is why, chances of survival for a premature baby improve as they near their due date.
In the last three months, the fetal features are refined, the finger nails reach the fingertips, the hair on the head grows further, the lanugo almost disappears, fat is deposited under the skin, and buds for the permanent teeth are laid down behind the milk teeth buds.
The fetus goes through periods of sleep and activity. It responds to bright light and loud noises. It gets to recognize your voice. It can also hear other external sounds like your partner`s voice, music etc. in addition to the noises inside your body like heart beat and digestion, circulation of blood within the uterus.
As your body prepares for birth, Weeks 34 to 36, the baby will start to move into its birth position. You might notice the baby "dropping," or moving down lower in your abdomen. This can reduce the pressure on your lungs and rib cage, making it easier to breathe. The unborn child gets into its favorite position, that is, lie usually head down. Your physician will examine your abdomen to determine the position adopted by the fetus. The procedure used is known as Leopold`s maneuvers.
Expectant Mother
 The uterus expands up to your breast bone. You may get indigestion and heart burns due to this crowding as also due to high level of progesterone. You will feel tired and experience shortness of breath. This is normal and is the effect of the expanding uterus pressing against your diaphragm and ribs. The increased pressure within your abdomen, the reduced return of blood from your lower limbs and the relaxation of the walls of blood vessels due to progesterone, may give you swollen ankles and hemorrhages in varicose veins. It`s important to get enough rest now, even though it can be more difficult to sleep as you get larger. The baby`s movements, bathroom runs, and an increase in your body`s metabolism can make sleeping difficult. Try these tips for sleeping in the last three months of pregnancy:
Avoid eating large meals three hours before going to bed
Do mild exercise like walking
Avoid taking long naps during the day
Talk with your partner, friends, doctor to relieve stress
You may see small red distortions on the skin in the final months of your pregnancy. These are vascular spiders appearing on your upper body. You may also notice reddening of palms, stretch marks on your thighs, abdomen and breasts. These stretch marks are called striae gravidarum. They are reddish in the time of pregnancy and becomes shining white after the baby`s birth. Do not apply lotions to prevent or reduce them. There is no evidence which says these lotions are effective in preventing or reducing stretch marks.
Very soon you will yearn for relief from the physical discomforts and look forward to the joy of having the baby. You will start thinking about labor and birth and child care. Go through the details of Labor and Birth and child Care given elsewhere in the document. Be sure to continue seeing your doctor regularly. In the last trimester of pregnancy, women usually see their doctors more frequently. From 30 weeks to 38 weeks of pregnancy, most doctors recommend one office visit every two weeks. After 38 weeks, women normally see their doctor every week until delivery.
As your due date approaches, ask questions and share concerns you have about labor and delivery. You and your doctor will discuss what kind of delivery you will have.
 Expectant Couple
A feeling of protectiveness will develop in you and your partner towards the unborn child. You will start thinking of the baby as a part of your family and will discuss and express your views to each other on the impending responsibilities of parenthood. Both of you may think of your own parents as role models.
You must communicate to each other and discuss your changing feelings, needs and necessary adjustments in sexual relationship.
The Thirty ninth and Fortieth Weeks of Pregnancy
Fetus
At 38 weeks the fetus is considered full term and will be ready to make its appearance at any time. Mom may notice a decline in fetal movement as the fetus is now filling the uterus with little room to move. The fetal organs continue to mature in the last two weeks.
The fetus keeps on gaining weight by fat accumulation and gains about one pound in these two weeks. The fetus is about 18 - 20 inches in length and weighs anywhere from5 1/2 lbs to 10 lbs. The average weight is about 7 lbs. And the average length is about 20 inches.
In the nine months of pregnancy, the weight of the fertilized egg has increased six billion times! In the next twenty years, weight will only increase twenty times.
Placenta
The placenta is a joint venture in which both mother and the baby invest tissues and other resources. It is the interface between the mother and the baby. It is part of the so-called `fetal supply line` from approximately the third month after conception until birth.
The placenta has the general form of a disc-like flattened cake moulded within the endometrial lining of the uterus. It has a diameter of approximately 6 to 8 inches and is about 1 inch thick centrally tapering towards the edges, and weighs about 500 grams (about 1/7th the weight of the fetus).
The surface of the placenta that originally faced the fetus has a shiny surface provided by the amniotic membrane that covers it. The umbilical cord generally arises from the centre of the fetal aspect of the placenta, and it also has a shiny covering of amniotic membrane that is continuous with that covering the placenta. The side of the placenta that implants in the uterine wall (the maternal side) is rough and bloody, and it is divided into lobes called cotyledons.
Variations in this arrangement are possible - sometimes the umbilical cord is attached to the edge of the placenta or even to the membranes beyond the margin of the placenta - but these differences appear to have little effect on normal function.
During its short but eventful existence, the placenta grows, differentiates, and matures, and some would even say shows signs of aging, before being ejected at the time of birth. It is not unusual to see areas of the placenta that have become calcified or degenerate, but fortunately these apparently age-related changes are not necessarily correlated with any fetal problems. Successful development of the placenta requires a co-operative effort between the extra-embryonic tissues of the conceptus and the endometrial tissue of the mother.
Umbilical Cord
The umbilical cord is the link between the placenta and the unborn baby. The umbilical cord is about the same length as the baby - 50 to 60 cms. It extends from the fetus` navel to the approximate center of the placenta The mature umbilical cord contains three large blood vessels: two umbilical arteries bringing fetal blood to the placenta, and a single umbilical vein returning blood to the baby`s heart. The radiating branches and tributaries of these vessels can be seen beneath the almost transparent coating of amnion on the fetal aspect of the placenta. It is moist and white and has a spiral appearance. Fetal blood flows at about four miles an hour, keeping the cord stiff like a garden hose full of water. At birth as your baby breathes, her circulation pattern begins to change, sealing off the blood flow to her navel and rerouting more blood to her lungs.
In the third stage of labor, the uterus expels the placenta along with the cord from the mother`s body. After the cord is separated from the placenta, the umbilical stub on the newborn`s belly dries and comes off after a few days. It leaves only a small scar (the umbilicus) behind.
In humans, the cord is clamped or cut after birth. The umbilical cord is made of Wharton`s jelly, not ordinary skin and connective tissue. There are no nerves, so cutting it is not painful. There is ordinarily no significant loss of either infant or maternal blood while cutting the cord.
Expectant Mother
As the baby "drops" down lower in your abdomen into the pelvic cavity, your profile changes. This descent is quite noticeable and is called engagement or lightening. You will find it easier to breathe or eat as there is less pressure on your diaphragm and ribs. At the same time, the baby`s head is now pressing against your bladder and you will need to pass urine more frequently. Towards the end there will be noticeable increase in frequency of the contractions in the uterus. These are called Braxton-Hicks contrac-tion, which have occurred intermittently throughout your pregnancy, help increase the efficiency of the uterine circula-tion. These contractions additionally prepare the cervix and uterus muscles for the imminent labor. As your pregnancy draws to a close and the fetal head presses into your pelvis, your cervix will become softer and thinner. This thinning is called effacement and is a sign of readiness for labor and birth.
You are coming towards the end of your long period of being pregnant, as though you have been and will be pregnant forever. A "nesting urge" will develop in you goading you with spikes of energy to prepare for your baby. Your weekly visits to your physician is all the more important, since it will give him an opportunity to monitor your body`s preparation for labor and birth.
Be happy. Pregnancy will be over soon and you and your partners will step into the world of parenting.
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