Walking down the street, don't you feel envious when you see beautiful and cute twins?
You might also think, "I wish I could have twins, and if they were a boy and a girl, that would be perfect!"
Wake up!
In the eyes of us obstetricians and gynecologists, having twins is not necessarily a good thing.
Because multiple pregnancies are inherently high-risk pregnancies, mothers carrying twins face higher risks and complications unique to multiple pregnancies than other mothers, naturally making the pregnancy more dangerous.
Having twins isn't easy; let's first understand how twins are formed.
Twins are divided into fraternal twins and monozygotic twins.
Dizygotic twins are formed from two separate eggs fertilized separately, while monozygotic twins are formed from a single fertilized egg. The two are fundamentally different.
Dizygotic twins
Dizygotic twins account for about 70% of twin pregnancies.
Everyone knows that IVF increases the chances of having twins, and twins conceived through assisted reproductive technology are mostly of this type.
But not all IVF treatments guarantee twins!
Because doctors usually transfer two embryos during the embryo transfer process to ensure a higher success rate, it is easy to conceive twins or triplets.
When one egg is paired with one fertilized egg, the resulting two fertilized eggs will naturally have different genetic makeup, and their sex, appearance, and personality will also show many differences.
Dizygotic twins usually have two placentas (though they can sometimes fuse into one), two amniotic cavities, and two layers of amnion and chorion in between, each with its own independent blood circulation.
Monozygotic twins
Monozygotic twins are two embryos that develop from a fertilized egg formed by the union of a sperm and an egg.
The two fetuses share the same genes, so their sex, appearance, and blood type are also very similar.
However, based on the timing of the division of the fertilized egg during early development, monozygotic twins are further divided into four types:
Dichorionic diamniotic sac
The amniotic sac splits within 3 days after fertilization, resulting in two amniotic sacs, two chorionic membranes, and one or two placentas.
Monochorionic diamniotic sac
The embryo divides 4-8 days after fertilization, at which point trophoblasts have differentiated. There is one placenta, and the two embryos are separated by two layers of amnion.
Monochorionic monoamniotic sac
The amniotic sac splits 9-13 days after fertilization, at which point the two fetuses share one amniotic sac and one placenta.
This situation is extremely dangerous because there is no amniotic membrane separating the two fetuses, making it very easy for accidents such as umbilical cord entanglement and knotting to occur.
conjoined twins
These are conjoined twins that people often see in the news.
Infants with thoracic fusion
This is because the division occurs on the 13th day after fertilization.
At this point, the primordial embryonic disc has already formed, and the organism can no longer completely divide.
Such fetuses have a very poor prognosis, and most cannot survive normally or have a very short lifespan.
Parasitic twins are a type of conjoined twins, which refers to a poorly developed cell cluster being directly encased in a normally developing embryo, resulting in incomplete fetal development.
Is being pregnant with twins really a good thing?
That's really not necessarily true.
Here's a set of data for you to get a feel for it:
The probability of developing gestational hypertension is 3-4 times higher for women with twin pregnancies than for women with singleton pregnancies.
The probability of developing intrahepatic cholestasis of pregnancy is twice that of a singleton pregnancy;
The probability of developing anemia is 2.4 times higher than in a singleton pregnancy;
The probability of miscarriage is 2-3 times higher than that of a singleton pregnancy;
The probability of premature birth is 7-10 times higher than in a singleton pregnancy;
The probability of birth defects in monozygotic twins is 2-3 times higher.
In addition, there are risks such as polyhydramnios, premature rupture of membranes, uterine atony, placental abruption, and postpartum hemorrhage.
If the pregnancy involves monochorionic twins, there is a risk of twin-to-twin transfusion syndrome because the fetuses share a placenta.
Twin-to-twin transfusion syndrome occurs when one fetus supplies blood to the other, ultimately leading to severe complications or even death in both fetuses due to abnormal blood circulation.
In addition, there are complications unique to monochorionic fetuses, such as selective fetal growth restriction and acardiac malformation in a single fetus.
I'm not trying to scare you by saying all this.
Mothers who are pregnant with twins, even if the babies are healthy, will experience greater pain and more severe early pregnancy symptoms during pregnancy.
For example, severe swelling in both lower limbs during pregnancy can make movement even more difficult.
We envy others because we don't see the risks and pain they endure, so it's best to just let things take their natural course!
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