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twins essay 1

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					Sierra Hoy

3-11-09

Period 8



       All babies are adorable, but twins have something special about them. It’s amazing

that there can be 2 people born at the same time who have the same looks, and may have

similar personality traits. If you didn’t know there are 2 types of twins- identical and

fraternal.

       Twins are 2 offspring resulting from the same pregnancy, usually born in close

succession. They can be the same or different sex. There are estimated to be approximately

125 million human twins in the world. The current rate in The United States is 31 twin

births per 1,000 women. Due to the limited size of the mother’s womb, multiple

pregnancies are much less likely to carry to full terms. Twin pregnancies usually last only

37 weeks. Since premature births can have health consequences for the babies, twin births

are often handled with special precaution. Multiple births are more common than they

were in the past.

       Some women are more likely than others to give birth to twins. Some factors that

increase the odds are: women in their thirties and forties have ovaries that are simulated to

produce more than one egg at a time. A woman is more likely to conceive a fraternal twin if

she is a fraternal twin, has already had fraternal twins, or has siblings who are fraternal

twins. Black African women have the highest incidence of twins, while Asian women have

the lowest.
       To begin, I will talk about identical twins, also known as monozygotic twins. Around

one in three sets of twins is identical. This occurs because the fertilized egg divides in two

while it is still a tiny collection of cells. The self contained halves then develop into two

babies, with exactly the same genetic information. These twins who differ in size may have

birth defects. Identifying identical twins at birth is important because it can improve

medical care throughout life. For, example, if one twin develops diabetes, the second twin

has a higher chance of getting the same disease. Usually monozygotic twins have a closer

relationship with each other. Identical twins look alike but they do not have the same

fingerprints. As they mature, they will become less alike because of lifestyle choices or

external influences. Monozygotic twins have nearly identical DNA. However, certain

characteristics become more alike as twins age, such as IQ and personality. Identical twins

can develop differently, due to different genes being activated. Monozygotic twins who

share a placenta can develop twin to twin transfusion syndrome. This condition means that

blood from one twin is being diverted into the other twin. One twin, the ‘donor’ twin, is

small and anemic, the other is large. The lives of both twins are endangered by this

condition. Identical twins always have the same hair and eye color.

       Now we have fraternal twins. Also known has Dizygotic twins. They usually occur

when two fertilized eggs are implanted in the uterine wall at the same time. Fraternal twins

may look similar, since they have the same age. However, they may also look very different

from each other. They can be the same or different sex. They are more common for older

mothers, with twinning rates doubling in mothers over the age of 35. Around two in three

sets of twins are fraternal. They can have different hair and eye color.
       There are some very rare twin cases, such as conjoined twins. These are twins whose

skin and internal organs are fused together. Conjoined twins occur once every two

thousand live births, and their survival is anything but assured. About forty to sixty

percent of conjoined twins are still born, and thirty five percent survive only one day.

Although more male twins conjoin in the womb than female twins, females are three times

as likely as males to be born alive. They are identical twins, and are always the same sex.

About seventy percent of all conjoined twins are girls. In this case, a woman only produces

a single egg, which does not fully separate after fertilization. They share the same placenta.

       There are about a dozen types of conjoined twins. One of the most common

classifications is thoracopagus twins. They’re connected at the upper part of the torso.

They share a heart, \which, depending on how closely they are joined, makes it nearly

impossible to separate and save them both. They make up about forty percent of all

conjoined cases. Another common type of conjunction is called omphalugus, where twins

are connected from the breastbone to the waist. They make up thirty three percent of all

conjoined twins. They may share a liver, but rarely share a heart.

The normal length of gestation for a single baby is around 40 weeks. However, gestation for

twins, identical or fraternal, is usually around 38 weeks. Childbirth can give rise to

complications when just one baby is present, so twins present extra difficulties. It’s advised

that mother’s carrying twins give birth in a hospital, rather than a home.

       Occasionally, a woman will suffer a miscarriage early in the pregnancy, yet the

pregnancy will continue; one twin was miscarried but the other was able to be carried to

term. The average weight of twins at term is about 5.5 pounds. The average weight gain for

averaged sized mothers of twins is between 35-45 pounds. Women pregnant with twins will
have more ultrasounds, tests and prenatal appointments than women pregnant with

singletons. The doctor will diagnose a twin pregnancy by listening with a stethoscope to

determine if there is more than one heartbeat, or by using ultrasound. There is a higher

rate of c-section with twins. It’s possible to have vaginal delivery, but it depends on the

position and weight of the babies, the mothers’ health, and the babies’ health. About thirty

five percent of twins are left-handed. Twins skip a generation, for example if you’re a twin

then you will not have twins of your own.

       It’s possible for fraternal twins to have different fathers. They are known as half-

twins. These siblings can be conceived if a woman has intercourse with 2 men in a short

time, and sperm from each man fertilizes an egg.

              A chimera is an ordinary person except that some of their parts came from

their twin or their mother. A chimera may be intersex, composed of cells from a male twin

and a female twin. In addition, in certain cases the person or chimera may have two sets of

DNA.

       When women are pregnant with twins, they need to eat a lot more. With one baby

you are supposed to add 300 calories a day to your diet. So when somebody is having twins

they need to add 600 to their diet. That should put them at about twenty eight hundred

calories each day. Women who are pregnant with twins can expect several differences from

a regular pregnancy. There will typically be more side effects such as nausea, vomiting and

heartburn with twin pregnancies. Mothers pregnant with twins sometimes experience high

blood pressure. There are a few delivery issues when it comes to having twins. Though it is

possible to deliver healthy twins vaginally, many doctors prefer for the mother to have a C-

section. If the babies are in a head-down position, a C-section may be performed. In rare
cases, the first baby will be delivered vaginally, but the twin may need to be delivered by C-

section due to complications.

       See twins are very special. There are many different types of twins who are unique

in their own way. Whether they are identical, fraternal, conjoined, or whatever they are

very special. As they grow up they may become very close, or may grow apart but they will

always be a part of each other.




                                    Sierra Hoy

				
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