Trimesters of Pregnancy and Stages of Labor

July 17, 2017

Pregnancy is a Latin word that means carrying of an offspring in a woman’s womb. A human pregnancy usually lasts for about 38 weeks or 9 months before a baby is delivered. A pregnancy starts after the fertilization of the mother’s egg by a sperm. The father ejaculates massive amounts of sperm and the successful sperm gets to fertilize the egg and in some cases more than one sperm fertilizes more than one egg in which the pregnancy results to carry twins. Human pregnancy is divided into three stages which are referred to as trimesters each lasting for about three months; the first, second and third trimesters.

The first trimester is the one with the highest risk of miscarriage. A pregnancy is said to have started after the implantation of the embryo into the uterus lining of the woman called the endometrial lining. It is measured from various start points like ovulation, chemical detection and day of last menstruation.

An ectopic pregnancy occurs when the fertilized egg implants itself in the fallopian tubes or in the cervix. Usually the onset of a pregnancy goes undetected by most women (Stoppard, 2009). However some women experience little bleeding from the egg implanting into the wall. It is during the first trimester when most women experience cramping. But this is usually of no threat to the mother or the baby unless there is bleeding or spotting involved.

After implantation the uterine wall, endometrium thickens and increases the number of blood capillaries passing through it. The placenta is formed partially by the decidua and partly from the outer layers of the embryo. The formed placenta serves to transport oxygen and nutrients to the embryo and also it removes waste products from the placenta.

During this period the mother experiences what is referred to as morning sickness and it lasts for more than seventy percent of the whole pregnancy period. During this stage the nipples darken because of an increase in hormones. It is during this stage when the risk of loosing the baby is the highest. Various biological and physical changes will occur at this stage for example the breasts become sore and tender and they will also increase in size, frequent urination, nausea and vomiting, insomnia, headaches, fatigue and dizziness.

The second trimester is marked by improved health of the mother. She feels much better at this stage. This stage extends from the 14th week up to the 20th week of the pregnancy. At this stage the hormone production is a leveled and the feeling of nausea and vomiting starts to go down though heart burn may result at this stage. The risk of miscarriage at this stage is low as compared to the first trimester.

The mother’s breasts start making colostrums as the arrival of the baby nears. Most women start getting their energy back at this stage of pregnancy and most of them start gaining weight. By the twentieth week the uterus will have expanded to more than twenty times its size. This is because the uterus is an elastic and muscular organ that is expanding so many times its size.

The fetus can be felt moving by this time a process referred to as quickening. This mostly happens at the 21st week for the first pregnancies or by 18th week if a woman has been pregnant before. Some women however do not feel the baby move up to until the third trimester. By this time the fetus is making its own insulin and its urinating so the uterus is fully functional.

The fetus can also be distinguished from being male or female. By this time the woman’s stomach has grown larger and bigger cloths are needed. The third trimester is the last stage of pregnancy. During this stage the woman gains the last weight it is usually the biggest weight change among all the three stages. It is also the stage when the fetus grows the fastest. It is thought that the fetus gains more than 27g a day. The belly also changes shape to drop downwards because the fetus starts to turn so as to face downwards towards the direction of exit. This is different from the second trimester when the belly is usually upright.

The fetus now can move more frequently and with more energy such that the movements become disruptive to the mother. The mother’s navel pops out due to her belly expanding. Most women are very uncomfortable at this stage with very frequent visits to the toilet, back pains and swollen legs. At this stage the baby can survive premature births with medical help (Resnik & Iams, 2003).

The development of the fetus can be divided into two; the embryonic and the fetal stages. The embryonic stage occurs for the first two months and nothing much is known about this stage. The fetal stage starts from the third month of the pregnancy. At this stage most of the structures of the body like the hands, head and feet are present and they start to develop. The heart is also present and the fetus can make some movements with its head. The brain and synapses develops until three to four months after birth.

The mother’s body changes during pregnancy to accommodate the new life growing inside. For example her body must increase the blood sugar so her blood circulation must be quickened which requires the heart to become enlarged to ensure this. As the pregnancy progresses the woman’s posture also changes. The back arches and the pelvis tilts to help the woman keep balance. The blood volume also increases tremendously especially during the first and second trimester. The pulmonary ventilation also increases to cater for the increased oxygen requirement. The mother’s metabolism also increases with increased gluconeogenesis and glycolysis.

Childbirth usually marks the end of a pregnancy with the birth of one or more babies. The process usually involves labor. In the normal child birth that is through the cervix the labor is divided into three stages; the dilation of the cervix, birth of the baby and the birth of the placenta. However these stages are eliminated if child birth is through caesarean section.

The first stage of labor starts when the cervix dilates. Some women may experience contractions at this stage and others may not. The actual labor is evident when the cervix starts to dilate progressively. Some women’s membranes may rupture at this stage with visible blood stains. The amniotic fluid also breaks at this stage. The mothers are advised to take deep breaths with each labour pain and then contract the abdominal muscles (Littleton & Engebretson, 2002).

This helps increase the intra- abdominal pressure which exceeds or equals the contractions of the uterus and helps increase the effectiveness of the abdominal contractions and make the birthing of the baby fast. As the baby passes through the cervix, pain increases especially at the stage where the baby’s head becomes engaged in the cervix and the uterus. When a contraction occurs, the muscles contracts and draws upwards from the lower segment of the uterus causing an expulsion movement pulling the cervix up the head of the baby. When the cervix is fully dilated it is the size of the babies head. Duration of labor varies differently over different women lasting up to eight hours for first time mothers and to less than four hours in women who have given birth more than once.

The second stage commences when the cervix is fully dilated that is when it is about 10cm for a baby that has been carried full term and the stage ends with the birth of the baby. When the second stage of labor starts the cervix is usually fully attached to the pelvis and the widest part of baby’s head at this time has already passed through the pelvis. At this stage the mothers help is needed through pushing to help the baby s head pass through the introitus.

The way the baby lies or its position and the shape and size of the mothers pelvis determines the way in which it passes through the cervix. The normal position of the baby in the uterus is the baby lies with its head facing the cervix and the back of its head is usually the mothers left side.

The baby’s head at this stage is visible and the mother may feel a burning sensation. And finally the baby comes .the extend of the second stage also varies depending on the preceding factors. The third and final stage is marked by the expulsion of the placenta which comes fifteen to thirty minutes after the birth of the baby.

Blood loss also occurs at this stage but it is controlled by the contraction of the uterus. The normal blood lose is about 600mL. The birth of the placenta can be achieved without medication that is by breastfeeding immediately after giving birth. Massaging of the uterus also helps to expel the uterus by stimulating contractions that help expel the uterus. Medical substances and drugs can also be used to help in expelling the uterus for example the use of oxytoxin is commonly used for this purpose. This drug causes violent uterine contractions that expel the placenta (Kee, Hayes & Connor, 1997).

The cavity of the uterus decrease greatly after the baby is born because the space the baby had occupied now remains empty.

Therefore the placenta becomes separated from its places of attachment on the uterus lining because the attachment ligaments of the placenta get smaller in size and it collapses into the uterus making it easy for it to be expelled from the uterus with the slightest efforts. Subsequent contractions of the uterus completely separate the placenta from the uterine lining into the vagina. After this the placenta is expelled but this third stage might be delayed by bleeding an occurrence which might call for surgery.

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Kee, J. L., Hayes, E. R. & Connor, M. (1997). Pharmacology: a nursing process approach. 2nd. Ed. Philadelphia: W.B. Saunders

Littleton, L. Y. & Engebretson, J. (2002). Maternal, neonatal, and women's health nursing. Cengage Learning.

Resnik, R & Iams, J. D. (2003). Maternal-fetal Medicine: Principles and Practice. 5th. Ed. Saunders.

Stoppard, M. (2009). Dr. Miriam Stoppard's New Pregnancy and Birth Book. New York: Ballantine Books.

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