Imagine you wish and try for one baby but end up with multiples! Research shows that there has been an increase in twin pregnancy the past few years. So this short guide aims to answer any questions you may have about giving birth to multiples with focus on identical twins and conjoined twins!
How do twins begin?
There are two kinds of twins: identical twins and fraternal twins. In the case of identical twins, the egg is fertilized and then splits into two cells. Each cell carries identical DNA and so both children will look exactly the same with only slight differences such as height or birthmarks.
Fraternal twins are not identical. Instead of having one egg that splits into two, there are two eggs that are fertilized by two different sperm at the same time so they could be of two different sexes with different physical characteristics.
Early signs of twin pregnancy
An early sign of twin pregnancy is excessive morning sickness and extreme fatigue. Morning sickness is common with all pregnant mothers but those who are giving birth to multiples tend to experience more morning sickness than usual.
Exhaustion is another early sign of twin pregnancy. Again, it is not uncommon for pregnant women to be more tired than usual but those who are having twins tend to undergo enhanced exhaustion.
Twins are hereditary and so if you are feeling excessively tired, are often nauseous and twins run in your family, you very well could be giving birth to multiples!
Twin pregnancy facts
With twins, you’ll have to prepare for double the trouble! This means you will probably be gaining more weight than with a single pregnancy. Due to this extra weight, a pregnancy with twins can often be more uncomfortable – severe exhaustion, stronger backaches and headaches, etc.
So get plenty of sleep and rest. Try a pregnancy massage, a great stress reliever to those giving birth to multiples. Also be prepared for a possible caesarian section, as with multiples this is the more common way of giving birth.
Because a twin pregnancy is considered a high risk pregnancy, you will probably need to consult your obstetrician more often than if you were having a regular pregnancy. Do not be fazed as this is quite common with twins.
Having a twin pregnancy is most certainly a mixed blessing. Whilst having two children is an amazing experience, the pregnancy itself can be tough. So make sure to take care of yourself.
Identical Twins
Twins are two people who have shared the same womb at the same time. They may also have come from the same egg.
Twin births are becoming more and more common due to several factors such as increasing use of fertility treatments, child births at an older age, and even genetic factors.
Women who are slightly above-average in build are also likely to have multiple births or twins. Certain ethnic groups are also found to have a greater twin population. One in every 250 births in the world could be an identical twin birth.
Monozygotic twins
Identical twins are also known as monozygotic twins. They are from a single egg that forms a single zygote that splits into two embryos. Two fetuses emerge from the two embryos in the same womb. The exact reason for this splitting hasn’t been identified yet.
How do identical twins evolve in relation to amniotic fluid and placenta?
It depends on the stage at which the zygote divides. For example, twinning at the earliest stages would result in diamniotic and dichorionic twins.
Twinning that occurs four to eight days after fertilization and eight to twelve days after fertilization results in monochorionic-diamniotic and monochorionic-monoamniotic twins respectively.
Sometimes, identical twins also share the same amniotic fluid, making them monoamniotic. Otherwise, they are diamniotic.
All monoamniotic twins are also monochorionic. Twins sharing the same placenta are monochorionic. Those who don’t are dichorionic.
Characteristics of identical twins
Identical twins are generally of the same sex. They have identical DNA and shared genes. They may be very similar to each other, almost like mirror images. Some twins can be told apart only by their fingerprints, teeth, handwriting, or any other intricate observations.
However, they have individually different personalities and character traits. Twins are generally emotionally attached to each other and are also believed to live longer because of this attachment.
Some people even believe that identical twins have their own language through which only the two of them can communicate. Some identical twins are also mirror twins—they are exact mirror images of each other.
Complications of twin pregnancy
Since identical twins share the same sac, amniotic fluid, and placenta, there could be some complications in pregnancy.
These could be a result of the entanglement of the umbilical cords or twin-to-twin transfusion syndrome because of the shared placenta. This may cause one or both the babies to be underdeveloped.
About one-fourth of all identical twins are mirror twins. Sometimes, one mirror twin may have a condition where some or all the internal body organs will be on the opposite side of the body. However, these are considered to be birth defects and are extremely rare.
Conjoined Twins
Twins are a kind of multiple births, i.e., when a woman gives birth to more than one baby at the same time. Twins occur when more than one egg is fertilized or when the same egg is fertilized more than once by one or two sperm, leading to formation of more than one fetus.
Conjoined twins are identical twins who are joined together somewhere in the body. Conjoined twins are monozygotic twins, in the sense that they share the same zygote.
Sometimes, they also share some vital internal organs. Formation of conjoined twins is believed to be the result of late twinning.
When the twinning occurs more than twelve days after fertilization of the egg, it may lead to formation of conjoined twins because the embryo may not split completely. This may be due to genetic or environmental factors.
Conjoined twins rarely survive
Conjoined twins are also known as Siamese twins, named after the famous conjoined twins, Eng and Chang Bunker from Siam. Conjoined twin births are very rare, amounting to around one birth in every 100,000 births.
Mary and Eliza Chulkhurst, famously referred to as the biddenden maids, are one of the earliest known set of conjoined twins. The ratio of male and female sets of conjoined twins was found to be three to one, and they are found more in certain countries like India or Africa.
Conjoined twins rarely survive because of the complexity of the bodies. Most of them are stillborn or die within twenty-four hours after birth. Conjoined twins can be separated surgically if none of the vital organs are involved.
Types of conjoined twins
Conjoined twins may be joined at any of these sites:
Chest (Thoracopagus)
The twins are joined face to face at the chest. They often have a shared heart and may also share one liver and upper intestine. This is one of the most common sites of conjoined twins.
Abdomen (Omphalopagus)
For Omphalopagus, twins are joined near the bellybutton. Many omphalopagus twins share the liver, and some share the lower part of the small intestine (ileum) and colon. They generally do not share a heart.
Base of spine (Pygopagus)
The twins are commonly joined back to back at the base of the spine and the buttocks. Some pygopagus twins share the lower gastrointestinal tract, and a few share the genital and urinary organs.
Length of spine (Rachipagus)
This is also called rachiopagus. The twins are joined back to back along the length of the spine. This type is very rare.
Pelvis (Ischiopagus)
For ischiopagus, the twins are joined at the pelvis, either face to face or end to end. Many ischiopagus twins share the lower gastrointestinal tract, as well as the liver and genital and urinary tract organs. Each twin may have two legs or, less commonly, the twins share two or three legs.
Trunk (Parapagus)
The twins are joined side to side at the pelvis and part or all of the abdomen and chest, but with separate heads. The twins can have two, three or four arms and two or three legs.
Head (Craniopagus)
The twins are joined at the back, top or side of the head, but not the face. Craniopagus twins share a portion of the skull. But their brains are usually separate, though they may share some brain tissue.
Head and chest (Cephalopagus)
The twins are joined at the face and upper body. The faces are on opposite sides of a single shared head, and they share a brain. These twins rarely survive.
There are also some rare kinds of conjoined twins, such as parasitic twins (where one twin is not completely formed and depends on the other twin to sustain life), and fetus in fetu (where one twin’s fetus is present inside the body of the other twin).
Some people consider separation of conjoined twins as unethical if it involves death or disability of one of the twins.
Conjoined twins, if they survive, can lead healthy lives. There are instances where conjoined twins have even married and become parents. The famous Siamese twins, Chang and Eng Bunker, fathered twenty-one children in thirty-one years.
Final thoughts on twin pregnancy
Healthy twins have the same needs as other newborns. However, you may need more rest and support than you imagined. For example, you need more support if your babies are born prematurely or need special medical care after birth.
Multiple pregnancy may also put you at higher risk of postpartum depression. So if you experience any symptoms of postpartum depression, speak with your doctor.
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References
American College of Obstetricians and Gynecologists (2019) Frequently asked question. Pregnancy FAQ188. Multiple pregnancy [Online]. Available at: https://www.acog.org/Patients/FAQs/Multiple-Pregnancy (Accessed: August. 05, 2019).
Bondeson, J. (1992) ‘The Biddenden Maids: a curious chapter in the history of conjoined twins,’ Journal of the Royal Society of Medicine, 85: 217 – 221. [Online]. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1294728/pdf/jrsocmed00112-0047.pdf(Accessed: August 05, 2019).
Mayo Clinic (2019) ‘Conjoined twins’ [Online]. Available at: https://www.mayoclinic.org/diseases-conditions/conjoined-twins/symptoms-causes/syc-20353910 (Accessed: August, 07, 2019).
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