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Boy and girl twins facts

All pregnancies start when a sperm fertilises an egg. This forms twins. These twins are called fraternal twins, dizygotic twins meaning two zygotes or non-identical twins. The technical name for this is dichorionic. Fraternal twins can be the same or opposite sex and their genes are as different as any other brother and sister.

SEE VIDEO BY TOPIC: Everything You Need To Know About Fraternal and Identical Twins - Dr. Sarah Finch


Fraternal Twins Facts

Twins are two offspring produced by the same pregnancy. North America and Europe have intermediate rates of 9 to 16 twin sets per 1, live births. Multiple pregnancies are much less likely to carry to full term than single births, with twin pregnancies lasting on average 37 weeks, three weeks less than full term. There is no known genetic link for identical twinning. The vast majority of twins are either dizygotic fraternal or monozygotic identical.

Less common variants are discussed further down the article. Among non-twin births, male singletons are slightly about five percent more common than female singletons. The rates for singletons vary slightly by country. For example, the sex ratio of birth in the US is 1. Zygosity is the degree of identity in the genome of twins.

Dizygotic DZ or fraternal twins also referred to as "non-identical twins", "dissimilar twins", "biovular twins", and, informally in the case of females, "sororal twins" usually occur when two fertilized eggs are implanted in the uterus wall at the same time. When two eggs are independently fertilized by two different sperm cells, fraternal twins result.

The two eggs, or ova , form two zygotes , hence the terms dizygotic and biovular. Fraternal twins are, essentially, two ordinary siblings who happen to be born at the same time, since they arise from two separate eggs fertilized by two separate sperm, just like ordinary siblings. This is the most common type of twin. Dizygotic twins, like any other siblings, will practically always have different sequences on each chromosome, due to chromosomal crossover during meiosis.

Like any other siblings , dizygotic twins may look similar, particularly given that they are the same age. However, dizygotic twins may also look very different from each other for example, be of opposite sexes. Studies show that there is a genetic proclivity for dizygotic twinning. However, it is only the mother who has any effect on the chances of having such twins; there is no known mechanism for a father to cause the release of more than one ovum. Dizygotic twinning ranges from six per thousand births in Japan similar to the rate of monozygotic twins to 14 and more per thousand in some African countries.

Dizygotic twins are also more common for older mothers, with twinning rates doubling in mothers over the age of Monozygotic MZ or identical twins occur when a single egg is fertilized to form one zygote hence, "monozygotic" which then divides into two separate embryos. Regarding spontaneous or natural monozygotic twinning, a recent theory proposes that monozygotic twins are probably formed when a blastocyst contains two inner cell masses ICM , each of which will lead to a separate fetus, rather than by the embryo splitting while hatching from the zona pellucida the gelatinous protective coating around the blastocyst.

Monozygotic twins may also be created artificially by embryo splitting. It can be used as an expansion of in vitro fertilization IVF to increase the number of available embryos for embryo transfer. Monozygotic twinning occurs in birthing at a rate of about 3 in every deliveries worldwide about 0.

The likelihood of a single fertilization resulting in monozygotic twins is uniformly distributed in all populations around the world. IVF techniques are more likely to create dizygotic twins. For IVF deliveries, there are nearly 21 pairs of twins for every 1, Monozygotic twins are genetically nearly identical and they are always the same sex unless there has been a mutation during development.

The children of monozygotic twins test genetically as half-siblings or full siblings, if a pair of monozygotic twins reproduces with another pair or with the same person , rather than first cousins. Identical twins do not have the same fingerprints however, because even within the confines of the womb, the fetuses touch different parts of their environment, giving rise to small variations in their corresponding prints and thus making them unique.

Monozygotic twins always have the same genotype. Normally due to an environmental factor or the deactivation of different X chromosomes in female monozygotic twins, and in some extremely rare cases, due to aneuploidy , twins may express different sexual phenotypes , normally from an XXY Klinefelter syndrome zygote splitting unevenly. Monozygotic twins, although genetically very similar, are not genetically exactly the same.

The DNA in white blood cells of 66 pairs of monozygotic twins was analyzed for , single-nucleotide polymorphisms known to occur in human populations. If they occur early in fetal development, they will be present in a very large proportion of body cells.


A study of 80 pairs of monozygotic twins ranging in age from three to 74 showed that the youngest twins have relatively few epigenetic differences. The number of epigenetic differences increases with age. Fifty-year-old twins had over three times the epigenetic difference of three-year-old twins. Twins who had spent their lives apart such as those adopted by two different sets of parents at birth had the greatest difference.


The authors were unable to predict whether a healthy fetus could result from a polar body twinning. In , a study argued that many cases of triploidy arise from sesquizygotic semi-identical twinning. See Semi-identical twins below, under Unusual twinnings. The degree of separation of the twins in utero depends on if and when they split into two zygotes. Dizygotic twins were always two zygotes. Monozygotic twins split into two zygotes at some time very early in the pregnancy.

The timing of this separation determines the chorionicity the number of placentae and amniocity the number of sacs of the pregnancy.

Dichorionic twins either never divided i. Monoamnionic twins divide after the first week. In very rare cases, twins become conjoined twins. Non-conjoined monozygotic twins form up to day 14 of embryonic development, but when twinning occurs after 14 days, the twins will likely be conjoined. It is a common misconception that two placentas means twins are dizygotic. But if monozygotic twins separate early enough, the arrangement of sacs and placentas in utero is indistinguishable from dizygotic twins.

DiDi twins have the lowest mortality risk at about 9 percent, although that is still significantly higher than that of singletons. Monochorionic twins share the same placenta , and thus have a risk of twin-to-twin transfusion syndrome.

Monoamniotic twins are always monozygotic. Monoamniotic twins, as with diamniotic monochorionic twins, have a risk of twin-to-twin transfusion syndrome. Also, the two umbilical cords have an increased chance of being tangled around the babies. Because of this, there is an increased chance that the newborns may be miscarried or suffer from cerebral palsy due to lack of oxygen. Mortality is highest for conjoined twins due to the many complications resulting from shared organs.

Dichorionic-diamniotic twins at 8 weeks and 5 days since co-incubation as part of IVF. The twin at left in the image is shown in the sagittal plane with the head pointing towards upper left.

The twin at right in the image is shown in the coronal plane with the head pointing rightwards. Abdominal ultrasonography of monoamniotic twins at a gestational age of 15 weeks. There is no sign of any membrane between the fetuses.

A coronal plane is shown of the twin at left, and a sagittal plane of parts of the upper thorax and head is shown of the twin at right. A study has found that insulin-like growth factor present in dairy products may increase the chance of dizygotic twinning. Specifically, the study found that vegan mothers who exclude dairy from their diets are one-fifth as likely to have twins as 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.

It may also be linked to the increase of growth hormones in food. About 1 in 90 human births 1. The widespread use of fertility drugs causing hyperovulation stimulated release of multiple eggs by the mother has caused what some call an "epidemic of multiple births ". Nevertheless, the rate of monozygotic twins remains at about 1 in across the globe. In a study on the maternity records of Hausa women living in the Savannah zone of Nigeria , there were 40 twins and 2 triplets per births.


Twins are more common in African Americans. Dizygotic twin pregnancies are slightly more likely when the following factors are present in the woman:. Women undergoing certain fertility treatments may have a greater chance of dizygotic multiple births. The risk of twin birth can vary depending on what types of fertility treatments are used.

With in vitro fertilisation IVF , this is primarily due to the insertion of multiple embryos into the uterus. Ovarian hyperstimulation without IVF has a very high risk of multiple birth. Reversal of anovulation with clomifene trade names including Clomid has a relatively less but yet significant risk of multiple pregnancy. A year German study [61] of 8, vaginally delivered twins that is, 4, pregnancies in Hesse yielded a mean delivery time interval of The study stated that the occurrence of complications "was found to be more likely with increasing twin-to-twin delivery time interval" and suggested that the interval be kept short, though it noted that the study did not examine causes of complications and did not control for factors such as the level of experience of the obstetrician, the wish of the women giving birth, or the "management strategies" of the procedure of delivering the second twin.

There have also been cases in which twins are born a number of days apart. Possibly the worldwide record for the duration of the time gap between the first and the second delivery was the birth of twins 97 days apart in Cologne, Germany, the first of which was born on November 17, Researchers suspect that as many as 1 in 8 pregnancies start out as multiples, but only a single fetus is brought to full term, because the other fetus has died very early in the pregnancy and has not been detected or recorded.


Twin Pregnancy Facts You Need to Know

When most people think of twins they think they are either Dizygotic fraternal twins that result when two eggs are fertilized or Monozygotic identical twins that come from a single fertilized egg that splits; but there are other types of rare and unique types of twins that you may not have heard about. Here is a run-down of some of the twin-types that are quite unusual and rare in our twin-world:. What happens when the egg splits and then each half meets a sperm?

I have a twin broski named Carl. Without further ado…here are seven things that I think only boy-girl twins would understand. But really, guys?

Did you know that some twins speak their own language, start playing together in the womb, and can be born years apart? In the words of Charlie Sheen well, sort of …Twinning! Brush up on your twosome health trivia here. According to a recent CDC report, the birth rate for twins has increased a whopping 76 percent since In fact, one in every 30 babies born in was a twin compared to , when the rate was one baby in every

7 Surprising Facts About Raising Twins

Fraternal twins each come from their egg and sperm. Identical twins are monozygotic, while Fraternal twins are dizygotic. Zygotic refers to zygote, the egg fertilized by the sperm that will develop into an embryo. Monozygotic twins come from a single egg and sperm that splits into two after conception. Fraternal twins are dizygotic, i. Each fertilized egg develops into an embryo and then a baby. Monozygotic twins or identical twins originate from a single fertilized egg, which splits into two, after conception. Many factors influencing multiple births are able only to impact fraternal twinning.

Fraternal Twins: Facts, Information and Common Questions

The number of twins in the U. According to a report by the National Center for Health Statistics , their birthrate rose 76 percent from to This could be due to the fact that more women over the age of 30 are having children and more are using fertility drugs and assisted reproductive technology, both of which increase the likelihood of multiple gestation. As many as one in three women who use fertility treatments may become pregnant with twins.

Unlike identical twins , this kind of twinning results in babies that have different sex and look different.

Twins are taking over! The rate of twin births jumped a whopping 76 percent from to in the U. Read on for more twin eye-openers. With so many mamas having twin babies these days, it may seem like being pregnant with two is no big deal.

The Difference Between Identical and Fraternal Twins


SEE VIDEO BY TOPIC: 10 Surprising Facts About Twins


25 Fascinating Facts About Twins

Genetics play a role a mother who is a fraternal twin herself has four times higher chance of producing twins , but other factors increase your chances too, including your age—moms over 30 have greater chance of releasing more than one egg at ovulation. Height is also a factor. Taller women have more insulin-like growth factor IGF which results in increased sensitivity of the ovaries. In addition, moms who are breastfeeding when they get pregnant are 9 times more likely to conceive twins even if you've weaned but breastfed for over 20 months, you have a higher chance for twins. And finally, diet.

of identical twins. But fraternal twins are much more common so read these interesting facts! 77 Kickass Baby Names For Girls And Boys With Meanings.

The majority of twins are fraternal twins twins that look different from one another. Learn more about fraternal twinning, from how they form to how they relate to each other, as well as how they differ from identical twins. Zygotic refers to zygote, the egg fertilized by the sperm that will develop into an embryo and grow into a baby. Monozygotic twins come from a single egg and sperm that splits into two after conception.

7 Things Only (Boy-Girl) Twins Will Understand

Out of all the twin types, boy-girl or opposite-sex twins have always been the most fascinating to me. After all, they get all the benefits of the twin bond without all the pressure. They have a play mate and confidant but by nature of their opposite sex, travel in different social circles and usually have vastly different interests and hobbies. It makes for a great life-long friend minus the comparisons and competition that same-sex twins sometimes come up against.

22 Wonderful and Wacky Facts About Twins

Dizygotic twins occur when two eggs are fertilized by two separate sperm. Dizygotic twins are also known as fraternal or non-identical twins. They are the most common type of twins. Monozygotic twins share percent of each other genes.

Toggle navigation. Fraternal Twins Facts Fraternal twins, which are non-identical twins, are also referred to as dizygotic twins, biovular twins, dissimilar twins, and if both babies are female, they can be referred to as sororal twins.

It is indeed a double blessing for a parent who has twins, but it is also double the trouble. Raising twins can seem tough at times, but there are also some amazing things about having twins. Fraternal twins are the most common type of twins, and they do not share the same genes. Here, you can find out more about the different kinds of twins, how they are interesting and some surprising fraternal twin facts. Fraternal twins or non-identical twins are either of a pair of twins who, as a result of developing from separate fertilized ova, are genetically distinct and not necessarily of the same sex or more similar in appearance than other siblings.

Learn important facts and risk factors for twin pregnancy. That's because there are growing numbers of older moms hormonal changes are believed to be responsible for the release of more than one egg at ovulation and more successful fertility treatments. Here are some other facts about twin pregnancies that you might not know, from Pregnancy Day by Day editor-in-chief Maggie Blott, M. Dorling Kindersley :. Research shows that 10 percent to 15 percent of all singleton births may have started off as twins; often one is lost early in pregnancy in a phenomenon known as "vanishing twin syndrome.

In This happens when the fertilised egg 'loses' one of the copies of the Y chromosome when it is dividing into two embryos in very early development. The resulting babies are then male XY and female XO.

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