Pregnacies with multiples

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Pregnacies with multiples

Postby chiggerbit » Fri Jun 26, 2009 6:51 pm

I've always found the topic of multiple births to be interesting, so am intrigued --and a bit alarmed--to hear that a nephew's fairly new wife is preggers with triplets. So, of course, I'm digging in with zest on the topic of pregnacies involving multiples, thought I'd post some of the nuggets that I dig up as I go along. Seeking tips and insights. The doctor seems to be sounding some serious alarms.
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Postby chiggerbit » Fri Jun 26, 2009 7:00 pm

One thing that I'm curious about is what the impact of irregular use of birth control pills might be on ovulation.
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Postby chiggerbit » Fri Jun 26, 2009 7:10 pm

I'm finding most of the information about multiples by searching on twinning. Wiki has a lot on fraternal (dizygotic) and identical (monozygotic) twins, but there's a paragraph there on "polar body twins". I've wondered about this for a long time. I roomed with a twins when I was in college. The doctor who delivered them had claimed they had to be identical twins because there was only one placenta, but they didn't look any more alike than the usual sisters do.

"...Another variety of twins, "polar body twins," is a phenomenon that was hypothesized to occur and may recently have been proven, very rarely, to exist. This would occur when a portion of a mature egg separates from itself. This is known as the first polar body, and it carries all the same genetic information as the egg. If polar body twins are fact, they would occur when two sperm fertilize both the egg and the first polar body. Generally the first polar body disintegrates. Polar body twinning would result in "half-identical" twins...."
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Postby chiggerbit » Fri Jun 26, 2009 7:24 pm

Apparently due to the timing of the splitting of the zygote in identical twins, there may be

a)a placenta with sac for each "zygote", or

b)a shared placenta for the zygotes but a separate sac for each one in that placenta, or

c)a shared sac and a shared placenta for all. Or any combination of these for multiples above two.

The earlier the splitting happens, the more likely the zygotes will have their own placenta and sac.

".... If the zygote splits very early (in the first two days after fertilization), each cell may develop separately its own placenta (chorion) and its own sac (amnion). These are called dichorionic diamniotic (di/di) twins, which occurs 18–36% of the time.[15] Most of the time in MZ twins the zygote will split after two days, resulting in a shared placenta, but two separate sacs. These are called monochorionic diamniotic (mono/di) twins, occurring 60–70% of the time.[15]

In about 1–2% of MZ twinning the splitting occurs late enough to result in both a shared placenta and a shared sac called monochorionic monoamniotic (mono/mono) twins.[15] Finally, the zygote may split extremely late, resulting in conjoined twins....."
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Postby chiggerbit » Fri Jun 26, 2009 7:31 pm

And I found this to be VERY interesting:

".....A recent study found that vegan mothers are five times less likely to have twins than vegetarian or omnivore mothers, and concluded that "Genotypes favoring elevated IGF and diets including dairy products, especially in areas where growth hormone is given to cattle, appear to enhance the chances of multiple pregnancies due to ovarian stimulation."[25]

From 1980–97, the number of twin births in the United States rose 52%.[26] This rise can at least partly be attributed to the increasing popularity of fertility drugs like Clomid and procedures such as in vitro fertilization, which result in multiple births more frequently than unassisted fertilizations do. It may also be linked to the increase of growth hormones in food;...."
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Postby chiggerbit » Fri Jun 26, 2009 8:33 pm

Things that can go wrong.

Of course, the obvious one is that the crowded quarters usually result in earlier delivery, a premature birth. But there are quite a number of other things that can happen in multiple pregnacies.

Vanishing Twin syndrome ... gtwin.html

Vanishing Twin Syndrome

Vanishing twin syndrome was first recognized in 1945. Vanishing twin syndrome is when one of a set of twin/multiple fetuses disappears in the uterus during pregnancy. This is the result of a miscarriage of one twin/multiple. The fetal tissue is absorbed by the other twin/multiple, placenta or the mother. This gives the appearance of a “vanishing twin”.
How is Vanishing Twin Syndrome identified?

Before the use of ultrasound, the diagnosis of the death of a member of a multiple pregnancy was made through an examination of the placenta after delivery. Today, with the availability of early ultrasounds, the presence of twins or multiple fetuses can be detected during the first trimester. A follow-up ultrasound may reveal the “disappearance” of a twin.

For example, a woman may have an ultrasound at 6 or 7 weeks gestation. The doctor identifies two fetuses and the woman is told she is having twins. When the woman returns for her next visit, only one heartbeat can be heard with Doppler. A second ultrasound is conducted and only one fetus is observed.

Sometimes a woman may have symptoms that would indicate a miscarriage, yet, with an ultrasound, a single baby is found in her uterus.

Vanishing twin syndrome has been diagnosed more frequently since the use of ultrasonography in early pregnancy. A conservative estimate of frequency is that vanishing twin syndrome occurs in 21-30% of multifetal pregnancies.
What is the cause of Vanishing Twin Syndrome?

The cause of vanishing twin syndrome is frequently unknown. Abnormalities that result in the vanishing twin appear to be present from early in development rather than from a sudden occurrence. Analysis of the placenta and/or fetal tissue frequently reveals chromosomal abnormalities, while the surviving twin is usually normal. Improper cord implantation may also be a cause.
What are the effects of Vanishing Twin Syndrome on the mother and surviving twin?

If the loss occurs within the first trimester, neither the remaining fetus nor the mother has clinical signs or symptoms. The prognosis of the surviving twin is usually excellent, but it depends on the factors that contributed to the death of the other twin. If the twin dies in the second or third trimester, there are increased risks to the surviving fetus. This could include a higher rate of cerebral palsy and a threat to the continuation of the pregnancy.

When a twin dies after the embryonic period of gestation (eight weeks), the water within the twin’s tissues, the amniotic fluid, and the placental tissue may be reabsorbed. This results in the flattening of the deceased twin from the pressure of the surviving twin. At delivery, the deceased fetus may be identified as fetus compressus (compressed enough to be noticed) or as fetus papyraceous (flattened remarkably through loss of fluid and most of the soft tissue).
What are the signs of a possible Vanishing Twin Syndrome?

Research indicates more cases in women over the age of 30 years.

Problems will usually begin early in the first trimester. The most common symptoms include bleeding, uterine cramps and pelvic pain.
What medical care is recommended for Vanishing Twin Syndrome?

No special medical care is necessary with an uncomplicated vanishing twin in the first trimester. Neither the surviving twin nor the mother would require medical treatment. If the fetal death is in the second or third trimester, the pregnancy may be treated as high-risk. Cerebral palsy may result in the surviving twin.

Pregnant women should seek medical care if they are experiencing bleeding, cramping and pelvic pain. They should be evaluated at a place with ultrasound capabilities. The use of an ultrasound is important to determine that no viable fetus remains before deciding if a D&C might be indicated. The woman can choose to wait for a natural miscarriage in many cases.
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Postby chiggerbit » Sat Jun 27, 2009 9:20 am

More on Vanishing Twin Syndrome.

Vanishing Twin Syndrome

Author: Ann L Anderson-Berry, MD, Assistant Professor of Pediatrics, Joint Division of Newborn Medicine, Creighton University, University of Nebraska Medical Center
Coauthor(s): Terence Zach, MD, Department Vice-Chair, Professor, Department of Pediatrics, Section of Newborn Medicine, Creighton University
Contributor Information and Disclosures

Updated: Sep 29, 2008Print ThisEmail This

Vanishing twin syndrome, first described by Stoeckel in 1945, is the identification of a multifetal gestation with subsequent disappearance of one or more fetuses. The rate of multifetal gestation at conception is higher than the incidence noted at birth.1 Vanishing twin syndrome has been diagnosed more frequently since the use of ultrasonography in early pregnancy.2,3 In vitro fertilization techniques have improved the understanding of vanishing twin syndrome because these pregnancies are closely monitored, and the number of implanted fertilized eggs is known.4

In vanishing twin syndrome, there may be complete reabsorption of a fetus, formation of a fetus papyraceus (ie, a "mummified" or compressed fetus), or development of a subtle abnormality on the placenta such as a cyst, subchorionic fibrin, or amorphous material.5

The timing of this event significantly affects the outcome of the viable twin and the maternal complications. For example, if the event occurs during the second half of pregnancy, the fetus could develop cerebral palsy or cutis aplasia, and the mother could develop preterm labor, infection, puerperal hemorrhage, consumptive coagulopathy, or obstruction of labor.6,7


Abnormalities that result in the disappearance of a fetus usually appear to be present from early in development rather than occurring from an acute insult. Placental or fetal analysis frequently reveals chromosome abnormalities. These abnormalities include diploidy, triploidy, and alternate sex chromosome results on placental pathology, skin biopsies, and chorionic villus sampling.8,9,10,11 Study findings of the viable twin chromosomes in these reports are normal. Therefore, it is thought that the vanished twin had a chromosomal abnormality resulting in disappearance.
United States

The frequency of multiple gestations is 3.3-5.4% at 8 weeks' gestation.1 Vanishing twin syndrome occurs in 21-30% of multifetal gestation.4

Research from a European series of pregnancies associated with assisted reproductive technology (ART) show that 10-15% of singleton births were initially twin gestations.

International prevalence is similar to that of the United States.
First trimester: Morbidity when vanishing twin syndrome occurs during the first trimester is limited. The mother is most likely to develop mild vaginal bleeding and cramping. If the event occurs later in the first trimester, morbidity may be similar to that of the second and third trimesters.
Second and third trimesters: Maternal complications include premature labor, infection from a retained fetus, severe puerperal hemorrhage, consumptive coagulopathy, and obstruction of labor by a low-lying fetus papyraceus causing dystocia and leading to a cesarean delivery.6
The diagnosis of vanishing twin in a pregnancy significantly increases both preterm (<37 gestational weeks) and very preterm (<32 gestational weeks) births.6
Fetal morbidity and mortality
In addition to loss of a twin, the surviving fetus has an increased risk of cerebral palsy, particularly if vanishing twin syndrome occurred during the second half of pregnancy.12
Other forms of morbidity reported in the surviving twin are aplasia cutis or areas of skin necrosis. In twins connected through vascular connection by placental anastomoses, temporary hypotension in the surviving twin at the time of fetal demise of the vanishing twin leads to poor perfusion and skin necrosis.13

No predilection for any race has been reported.

No predilection for either sex has been reported in the vanishing twin.

Researchers report more cases in women older than 30 years. Advanced maternal age is also a recognized risk factor for fetal and placental chromosome abnormalities.

Problems usually develop during the first trimester of pregnancy. The most common presenting complaints include bleeding, uterine cramps, and pelvic pain.14

Vaginal bleeding may be observed on pelvic examination.14

The cause of vanishing twin syndrome is frequently unknown; however, this condition occurs more often in fetuses with genetic or chromosomal abnormalities.5 Improper cord implantation may also play a role in some cases.
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Postby chiggerbit » Sat Jun 27, 2009 9:44 am

The next syndrome is Twin to Twin Transfusion Syndrome, or TTTS

Twin to Twin TransfusionSyndrome (TTTS)

Twin to twin transfusion syndrome (TTTS) is a serious disorder that occurs in identical twins and higher order multiples who share a placenta. This occurs when there is a connection in the two babies’ blood vessels of their shared placenta. This results in one baby (this twin is referred to as the recipient) receiving more blood flow, while the other baby (this twin is referred to as the donor) receives too little. Twin to twin transfusion syndrome is also referred to as chronic intertwin transfusion syndrome.

How often does Twin to Twin Transfusion Syndrome occur?

TTTS occurs about 15 percent of the time among identical twins. Fraternal twins are not at risk for this syndrome because they do not share a placenta.
What can I do to make sure my twins do not develop Twin to Twin Transfusion Syndrome?

TTTS is a random event that cannot be prevented by doing or not doing any specific thing. It is not a genetic disorder nor is it a hereditary condition.
How is Twin to Twin Transfusion Syndrome diagnosed?

Your healthcare provider may suspect this disorder if any of the following is seen during an ultrasound:
Marked difference in the size of fetuses of the same gender
Difference in size between the two amniotic sacs
Difference in size of the umbilical cords
A single placenta
Evidence of fluid build up in the skin of either fetus
Findings of congestive heart failure in the recipient twin
Polyhydraminos (excess amniotic fluid) in the recipient twin
Oligohydraminos (decreased or too little amniotic fluid) in the donor twin
Does the mother have any signs of Twin to Twin Transfusion Syndrome?

A mother whose twins have TTTS may experience:
Sensation of rapid growth of the womb
A uterus that measures large for dates
Abdominal pain, tightness, or contractions
Sudden increase in body weight
Swelling in the hands and legs in early pregnancy
What treatment options are available for Twin to Twin Transfusion Syndrome?

Up until recently twin to twin transfusion syndrome has claimed the life of both babies, but technology has brought about two new treatment options for this condition. The use of amniocentesis to drain off excess fluid appears to improve the blood flow in the placenta and reduce the risk of preterm labor. Amniocentesis can save approximately 60% of affected babies. Laser surgery can also be used to seal off the connection between the blood vessels and appears to save 60% of affected babies. Delivery is also an option if your healthcare provider determines the twins’ lungs have reached maturity.
What are the advantages of having laser surgery instead of an amniocentesis?

Amniocentesis may need to be done repeatedly throughout the pregnancy to maintain proper blood flow in the placenta, while laser surgery usually only requires one treatment.
What are the potential complications of Twin to Twin Transfusion Syndrome?
Premature labor either due to ruptured membranes or induction
Respiratory, digestive, heart, or brain defects in the recipient
twin because of excess fluids
Donor twin developing anemia
Fetal demise/death
Is there anything else that I need to be aware of if I have been diagnosed with Twin to Twin Transfusion Syndrome?

The Twin to Twin Transfusion Syndrome Foundation recommends that weekly ultrasounds be performed after 16 weeks through the end of the pregnancy to monitor TTTS. They recommend that this be done even if the warning signs of TTTS have decreased.
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Postby chiggerbit » Sat Jun 27, 2009 9:59 am

More on Twin to Twin Transfusion Syndrome: ... re_q6.html

Twin to Twin Tranfusion Syndrome

Ciara, left at 4lbs 10 oz and Alexa 2lbs 5 oz

NOTE: The following information is provided for your information only and does not necessarily reflect each person's individual situation. If you have any concerns whatsoever about your pregnancy, please consult your physician immediately.

Twin to twin transfusion syndrome (TTTS) is a random abnormality of a monochorionic placenta that causes one identical twin to receive less than normal amounts of blood supply during pregnancy while the other receives too much. The babies share blood vessels in their placenta that cause an imbalance of blood flow and nutrients between them. There are degrees to the severity of the syndrome, but it is always life-threatening due to the fact that it can worsen at anytime during pregnancy. Below is a summary of the difference between dizygotic (fraternal) and monozygotic (identical) twin pregnancies. TTTS can only happen with monozygotic twins, or as a pair in a higher multiple pregnancy, that share a single monochorionic placenta. (Read Story)

There are two types of twins:

DIZYGOTIC (DZ) - two eggs meet up with two sperm. These babies are technically siblings who happen to have been born at the same time. They are commonly known as "fraternal". They always have one placenta each and are called dichorionic (DC).

MONOZYGOTIC (MZ) - one egg meets up with one sperm. These babies are always the same gender and are commonly known as "identical". MZ pregnancies can experience high complication rates, particularly if the twinning process occurs more than 4 days from fertilization resulting in a single monochorionic placenta share by two or more babies.

There are two types of monochorionic pregnancies that can be affected by twin to twin transfusion syndrome:

When the embryo randomly splits between 4-8 days after conception, the pregnancy results with two babies each in their own amniotic sac (diamnionic) as well as sharing a placenta (monochorionic). The majority of these pregnancies proceed without complications. However, approximately 15% of the time, the babies will share blood between them disproportionately and warning signs of the syndrome will appear on ultrasound (see warning signs below). The syndrome can occur with two or more babies in a higher multiple birth pregnancy as long as the babies share a single monochorionic placenta.

When the embryo randomly splits between 8-12 days after conception, the pregnancy results with both babies sharing a single placenta (monochorionic) but the babies are in the same amniotic sac (monoamniotic). This type of pregnancy can still result in TTTS but it is more difficult to diagnose with the babies in the same sac. Also, there is a greater concern that the babies' cords will become entangled. It is estimated that approximately 50% of the babies will pass away from cord entanglement. It is recommended that mothers be hospitalized at 24 weeks for 24 hour monitoring of the babies until they are born.

One of the warning signs of TTTS shown on ultrasound is a size difference in the babies. One baby, the donor, becomes restricted in growth receiving less then normal blood flow. The donor baby does not urinate very much and has little to no fluid in his or her amniotic sac. Sometimes the baby is referred to as a 'stuck twin' or having oligohydramnios. Subsequently, a much larger blood flow goes to the co-multiple, referred to as the recipient twin. Due to the shared, interconnecting veins and arteries in the single placenta, the blood disproportionately flows through the donor twin and collects in the recipient twin, who is unable to efficiently rid his or herself of the extra blood. The recipient baby urinates frequently causing too much amniotic fluid or polyhydramnios. Because of this abnormality in the placenta, both babies' well-being can be severely compromised.

It is important to understand that one reason babies can become growth restricted is that the babies may share the placenta itself unequally. The donor baby could have less then half of the placenta to nourish it. This is one reason why The Twin to Twin Transfusion Syndrome Foundation advocates weekly ultrasounds from 16 weeks through delivery of the babies. If a baby has a small placental share, and you cannot know prior to birth for sure what the placental share is, the baby will get to a certain gestational week and it will stop growing. The baby will not get enough blood and oxygen from it s share of the placenta to 'get bigger' than the size that it is. The rate of growth for the babies is extremely important and is often overlooked. The sharing of the blood from the syndrome also adds to size differences of the babies. TTTS is often combined with an unequal placental sharing.

Some treatment options are available:

AGGRESSIVE SERIAL AMNIOCENTECES removal of the excess fluid around the recipient which may need to occur several times;

LASER SURGERY which identifies the connecting blood vessels in the shared monochorionic placenta and cauterizes them with a laser beam. The babies are being separated in the placenta so each will then get their blood supply independently from the other. The scope used is inserted through amniotic cavity of the recipient baby. There are specific criteria that must be met based on ultrasound findings.

BEDREST AND NUTRITION which is explained below and combined with the therapies listed above.

What Can We, as Parents, Do?
Make sure your obstetrician has plenty of high-risk pregnancy experience.
Make sure that your obstetrician uses intensive ultrasound to determine the chorionicity (DC or MC) of the babies as early as possible in the pregnancy. If the babies are like-sexed, you need to know if they share a placenta or each have their own. If they share a placenta, weekly ultrasounds are crucial in the care of your babies and you may have to really fight to have them. Don't take no for an answer. If the babies are unlike-gender, they must be fraternal twins and cannot have TTTS. Keep asking questions until you are satisfied and understand the answers.
If your babies are monochorionic, take really good care of yourself. One way is to follow advice from Dr. Julian De Lia who pioneered laser surgery almost 20 years ago. He is now recommending adding protein drinks to your diet, such as 3 cans of Boost drinks a day. He feels that TTTS can make mothers malnourished adding to the fluid problem around the recipient babies. Drinking the protein can help get the protein in your blood back to normal. Many women have seen improvements from this. Nutrition is completely overlooked by most doctors. Bedrest is also strongly encouraged along with adding liquid protein. Bedrest is defined as laying horizontally on your left side and getting up to eat, shower, use the bathroom, and go to appointments. Laying on your left side takes pressure off of your cervix and helps increase blood and oxygen to the placenta to help your babies.
Make sure that your cervix is checked weekly. This is also overlooked by many doctors. If your cervix length shortens to 2cm or less, a cerclage or stitching of the cervix can be done up through 25 weeks. This has saved many pregnancies. Laser surgery can still be done after a cerclage only through the 26th week.
If early signs of TTTS appear, or there is a sudden increase in your size, ask for a perinatology appointment immediately. Your feto-maternal medicine specialist will know about the options for treatment. Ask what they think about possible laser treatment and whether this is a possibility for you. Once again, don't take no for an answer. It is also encouraged by The TTTS Foundation to contact the laser doctors on your own so you get the correct and up-to-date information directly from the doctors who perform the procedure.
Understand a monochorionic placenta and what TTTS is. Understand specifically what is happening to your babies with measurements of their size difference, your fundal height, the biggest pocket of fluid around each baby, where your placenta is located in the uterus, their doppler readings and your cervix. Create a medical plan of action with back-up plans so you can be as prepared as you can for each appointment.
Warning Signs of TTTS

- a large-for-dates uterus
- water in baby(ies) body (heart failure called hydrops)
- a single placenta
- same sex babies
- growth discordance, babies are growing at different rates
- too much amniotic fluid in one sac and too little in the other
- being 16-26 weeks pregnant with fundal height of 30 cm or more
- a doppler reading for the babies which is absent diastolic or reverse flow
- a cervix which is thinning and shortening to 2cm or less
- sudden weight gain and/or swelling in the mother's body

The TTTS Foundation says that without treatment, the death rate for twins who develop TTTS at mid-pregnancy (16 to 26 weeks gestation) may be as high as 80-100, mostly as a result of premature delivery. The later the condition develops in the pregnancy, the better chance the babies have since they could be delivered if signs of distress are present. Your health care professional is the best source of information regarding your personal situation and can discuss fully with you how your situation can be managed. However, remember that the ultimate decisions for your children are yours.


Diamniotic twins: twins who have developed in separate amniotic sacs. They may be either dizygotic or monozygotic.

Dichorionic twins: twins who have developed in separate chorionic sacs. They may be either dizygotic or monozygotic.

Dizygotic twins: twins formed from two separate zygotes.

Fraternal twins: see dizygotic twins

Higher order multiples: triplets, quadruplets, quintuplets or more

Hydropic (hydrops): a condition due to the abnormal accumulation of serous fluid in the tissues or in a body cavity

Identical twins: see monozygotic twins

Monoamniotic twins: twins who have developed in a single amniotic sac. These twins are always monozygotic.

Monochorionic twins: twins who have developed in a single chorionic sac. These twins are always monozygotic.

Monozygotic (monozygous) twins: twins formed from a single zygote.

Oligohydramnios: the presence of too little amniotic fluid around a baby.

Polyhydramnios: the presence of too much amniotic fluid around a baby.

Serous fluid: a thin and watery fluid

Twin to twin transfusion syndrome (TTTS): results from abnormalities of the placenta in monozygous twin pregnancies. TTTS results from blood passing disproportionately (transfusing) from one twin baby to the other through connecting blood vessels within the shared (monochorionic) placenta. (TTTS Foundation)

Zygote: a fertilized ovum.

Written by:
Lynda P. Haddon, Multiple Birth Educator
Last edited by chiggerbit on Sat Jun 27, 2009 10:54 am, edited 1 time in total.
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Postby chiggerbit » Sat Jun 27, 2009 10:54 am

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Postby chiggerbit » Sat Jun 27, 2009 11:58 am

Ok, found the incidence rate here:

"....Approximately 20 percent of all twin pregnancies are monochorionic [identical--chig], and the incidence of Twin-Twin Transfusion Syndrome / TTTS in monochorionic [identical] diamniotic [two sacs?] gestations is approximately 10 to 20 percent....."
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Postby chiggerbit » Sat Jun 27, 2009 4:29 pm

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Postby chiggerbit » Sun Jun 28, 2009 9:33 am

I don't understand what this means:

Triplets can be monozygotic, dizygotic, or trizygotic. Trizygotic triplets occur when 3 sperm fertilize 3 ova. Dizygotic triplets develop from one set of monozygotic cotriplets and a third cotriplet derived from a different zygote. Finally, 2 consecutive zygotic splittings with one split results in a vanished fetus and monozygotic triplets.
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Postby RomanyX » Mon Jun 29, 2009 12:25 am

Thanks for all this info, chiggerbit. :)
Oh Perfect Masters,
They thrive on disasters;
They all look so harmless
'Til they find their way up there...
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Postby chiggerbit » Wed Jul 01, 2009 9:49 pm

Ok, back to the basic kinds of twins. There are the dizyogitc twins and the monozygotic twins. Dizygotic twins are the fraternal twins, which are like plain old siblings who happen to share their mom's uterus at the same time--two ovum fertilized by two sperm, with a placenta and sac for each one. Dizygotic twins can be two girls, two boys, or one of each. Same goes for higher numbers, such as dizygotic triplets. Or do they call it tri-zygotic? Have to check that out. We're seeing a lot more of these kinds of twins due to fertility treatment. But each baby has it's own bedroom in the apartment. in addition, the pregnacy can be both dizygotic AND monzygotic, if there are more than twins, such as when Octomom had six pre-fertilzed eggs implanted, and two of the eggs separated into monzygotic sets of twins, so a total of eight babies.

That's pretty much all that can be said about dizygotic kind of twins, right.? Well, except there is also a somewhat different kind of fraternal twin situation, for which I can find no name except for the name of the uterine condition which can lead to this kind of twin births. This uterine condition is called uterine didelphys, UD, or double ueteri, in which it is posible to get pregnant in each uterus, at the same time or even at different times, and possible to deliver at widely-different times. Two uteri, each half the size of a regular uterus means that at 20 weeks, the baby can begin outgrowing its home. This condition can also result in a single pregnacy or multiples of more than two, dizygotic or monozygotic. Besides the complications caused by smaller uteri, these pregnacies are also at more risk due to higher risk of ectopic pregnancies, as well as labor obstructions caused by having two uteri.
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