Twins baby are no longer a surprise of nature as they are quite common. Most people know how they occur in a pregnancy. Generally, twins are formed in one of two ways: Identical twins occur when a single fertilized egg splits into two. The resulting babies share the same genes, are of the same sex and look almost completely alike. Fraternal twins, on the other hand, occur when two separate eggs are fertilised by two separate sperm. The babies do not share the exact same genes, can be of different sex like a boy and a girl, and are no more alike than they are to their siblings from different pregnancies.
That’s the 101 of the twinning story. But creating and successfully carrying multiples is not as simple as that. The human body is full of mystery and pregnancy is like a genetic pinball machine where random probabilities could trigger off a chain reaction that impacts the outcome. And when it comes to being pregnant with multiples ─ things could get really complicated.
For example, did you know that there are twin types called MoMo, MoDi and DiDi? Serious! It is important to know what type of twins baby you are carrying as having one or the other carries a risk ratio that could make the difference between a pregnancy of double joy or double trouble.
If you’re pregnant with twins or hoping and wondering on how to get pregnant with twins baby, there are some tips below on how you can achieve this. But first, here are some basics about twins baby.
Questions & Answers
1. Do Twins Share One Amniotic Sac, One Placenta and One Umbilical Cord?
Here is a question that has seldom been asked. While it is understood that there will be two fetuses sharing a uterus, do they also share all of the resources such as the amniotic sac and placenta inside? The answer is: It depends on whether they are Fraternal or Identical twins and if they happen to be the latter, again, it depends.
Fraternal Twins
Fraternal twins are also known as false twins for a reason. Fraternal twins are actually two separate fertilised eggs. Because they are two individuals, they develop their own separate amniotic sacs, placentas, umbilical chords and other supporting structures.
Identical Twins
Identical twins, on the other hand, are split from one fertilised egg. Whether or not they share the same amniotic sac and the placenta depends on how early or late that single fertilised egg was divided into two. However, they will always have their own umbilical cords whether or not they share the placenta and/or amniotic sac.
Sharing can only happen with Identical twins, never Fraternal ones.
Generally speaking, the more resources Identical twins share, the more dangerous the pregnancy becomes. For one, the sharing of the placenta is seldom 50-50 because of where the fetuses may implant on the organ. There are no set rules or blueprint for this. One twin may implant at a prime position and get the lion’s share of the oxygen and nutrients while the other gets deprived of everything he needs to grow and develop properly. It is always safer for the lives at stake when twins have their own separate placenta and amniotic sacs. However, a mother or a doctor cannot set the condition or determine this.
2.What Timeframe will the Splitting of the Egg have to Occur to Determine How Much the Twins will Share?
A. If the egg splits very early like from Day 1 to Day 3 after fertilization, then it will result in two amniotic sacs and two placentas ─ one set for each twin (just like Fraternal twins). According to Children’s Hospital Wisconsin, about 30% of pregnancies with Identical twins occur this way.
B. If the egg splits from Day 4 to Day 8 after fertilization, then the twins will have separate amniotic sacs but share one placenta. The majority (like 70%) of Identical twins split at this stage.
C. If the egg splits late such as from Day 8 to Day 13 after fertilisation, then the twins will share one amniotic sac and one placenta (both babies in one sac and sharing one placenta). This type of twinning is extremely high risk due to possible umbilical cord entanglement, knotting and compression, mixed up circulation and blood vessels (from babies to mother and baby to baby) because nothing is separating the babies. The good news is ─ occurrence is rare as it only accounts for about 1% of Identical twins. Survival for this type of twinning is low. The twins are usually also born very premature.
D. If the egg splits even later such as after Day 13 such as from Day 14 to Day 15 after fertilization, then Conjoined twins occur as they cannot separate completely after this time. This occurrence is, however, even rarer, like one in 200,000 live births.
When Timing is Everything
3. What are MoMo, MoDi and DiDi Twins?
- MoMo Twins
According to Wikipedia, Identical twins that share one amniotic sac and one placenta are medically called Monoamniotic-Monochorionic twins. (Mono means one and Chorion ─ a Latin word ─ refers to the placenta).
Monoamniotic-Monochorionic twins are thus usually called “MoMo” or “Mono-Mono” twins. They are explained in Point C of the TimeTable above. This type of twins are at the highest risk and their survival rate is often low.
Listen to what Associate Professor Boonsri Chanrachakul, Ob/Gyn Specialist of the Preterm Prevention Clinic, Samitivej Hospital has to say about these twins:
- MoDi Twins
MoDi stands for Monochorionic-Diamniotic meaning one placenta but two amniotic sacs. (“Mono” means one and “Di” means two). MoDi twins are almost always Identical although sometimes they can be Fraternal due to the placentas of the babies growing and overlapping to the point it is impossible to determine whether there is one or two placentas. MoDi twins are not as high risk at MoMo twins, but are at higher risk than DiDi twins. Like MoMo twins, MoDi twins are also at risk for TTTS.
TTTS stands for Twin-Twin Transfusion Syndrome ─ a rare, serious condition that can occur when Identical twins share a placenta. Abnormal blood vessel connections form in the placenta and allow blood to flow unevenly between the babies.
If TTTS occurs, it is easier to diagnose MoDi twins than MoMo twins because they each have their own amniotic sac. Doctors are able to diagnose TTTS by measuring the fluid in each baby’s amniotic sac. Because they share a placenta, MoDi twins are usually delivered by week 36 due to concerns over placenta deterioration.
- DiDi Twins
The name DiDi comes from the “Di” word (which means two) in reference to their type as Dichorionic-Diamniotic twins. DiDi Twins are the most common twin type. DiDi twins can be either Identical or Fraternal and are the lowest risk type of twin pregnancies. They are higher risk than a singleton pregnancy, but the lowest as far as twin pregnancies go because they have their own placentas and their own amniotic sacs. DiDi twins are explained in Point A of the TimeTable above.
4. Do Twins Baby Run in the Family? Who Passes the Twin Gene ─ Mother or Father?
So far, there is no evidence that Identical twins run in families. To date, science says the splitting of the egg into Identical twins occurs at random. However, Fraternal twins are due to genetics. A couple is more likely to have Fraternal twins if twinning runs in the woman’s family; so says this study.
Who passes the twin gene? Mother does. The gene for hyperovulation is passed down from parent to child and since only women ovulate, they determine twins in the family. If mother passes the gene to her son, he can’t make his wife give birth to twins but he can, in turn, pass it on to his daughters who may then have multiple births when they marry. Apart from being passed down from generations, the frequency of hyperovulation ─ the term given when a woman releases more than one egg from her ovaries during her monthly cycle ─ also increases with maternal age.
Women over the age of 35 are more likely to have twins. And women who are fraternal twins or have a set of fraternal twins as siblings are 2.5 times more likely to have twins than an average woman.
4. So You Want Twins? What are the Factors that can Influence your Chances?
Among obvious factors like a family history of your mum’s side having twins, your ethnicity (Asians have fewer chances than African and Caucasian women) and you having given birth to twins baby before, your age, weight and diet also play a major role.
As mentioned, women above 35 are more likely to have twins, and those with higher body mass index (BMI) have higher chances of carrying twins. In other words, slim, younger women especially those on a vegan or low fat diet are less likely to have twins. The diet for getting twins is eating lots of protein and milk as well as folic acid and of course ─ fertility medications and In Vitro Fertilisation (IVF). The last two can almost guarantee twins.
For more fascinating insights on twins baby and others, visit Motherhood.com.my.