Everyone is fascinated by multiple pregnancies, scientists and even non-scientists share this wonderment, but how common is it?
Well, around one in every 89 live births is a twin, for triplets, it’s one in every 7900, and for quadruplets, one in every 705 000 live births result in four babies being delivered.
Now, if you’re expecting multiples, you’ll soon become quite familiar with terms like Zygosity, Chorionicity, and Placentation. And, it won’t be long before everything you thought you knew about pregnancy will be thrown out the window.
To help us decipher this new world you’re entering, Chair in Obstetrics and Gynaecology and Professor Fetal Medicine, Head of Discipline Obstetrics and Gynaecology at the University of Newcastle and John Hunter Hospital Professor Craig Pennell says at first it might be quite confusing but learning what type of multiples you’re carrying will help you make sense of what’s to come.
“Fraternal twins are non-identical and they are doing nothing more than sharing the same uterus. They have the same genetic similarities as brother and sister or brother and brother from two separate pregnancies,”
“If there is good evidence on the early imaging that you have two versions of everything, so Dichorionic Diamniotic twins, then that pregnancy almost always goes very smoothly,”
“If there is good evidence on the early imaging that you have two versions of everything, so Dichorionic Diamniotic twins, then that pregnancy almost always goes very smoothly.”
~Professor Craig Pennell~
“If you have a Monochorionic twin pregnancy, you’re going to need to make sure you have someone experienced in looking after that type of twins,” explains Professor Pennell.
Professor Pennell says it really is very different having an identical twin pregnancy to having a non-identical twin pregnancy and it’s important to understand that.
He goes on to explain the different types of multiples and how it requires significant skill in diagnosing certain types.
- Non-identical twins who have the same genetic similarities as brother and sister or brother and brother from two separate pregnancies.
- Dizygotic, which are two zygotes (two eggs fertilised by two sperm).
- Twins of different gender, which can be seen on ultrasound often as early as 12 weeks and will be a Dichorionic pregnancy with two placentas.
- If there are two placentas, one on the back wall and one on the front wall and they’re completely not in contact with each other, and of the same gender, they are probably dizygotic.
“Fraternal twins are non-identical and they are doing nothing more than sharing the same uterus. They have the same genetic similarities as brother and sister or brother and brother from two separate pregnancies.”
~Professor Craig Pennell~
- Monozygotic, which is one egg fertilised by one sperm and then that egg divides during the first two weeks after fertilisation.
- The timing of the split will determine the type of pregnancy:
- Monochorionic pregnancy has one placenta,
- Dichorionic pregnancy – the egg splits very early on and you end up with two placentas and two implantation sites.
Some are identical.
Some are non-identical (fraternal).
Each twin has their own amniotic sac.
“If you have a Monochorionic twin pregnancy, you’re going to need to make sure you have someone experienced in looking after that type of twins.”
~Professor Craig Pennell~
Each twin has their own amniotic sac.
Share the same amniotic sac, which poses increased risks during pregnancy and requires significant monitoring.
Sally's Story - MoDis
Looking back at the early stages of my twin pregnancy, I am amazed that I had no idea I was pregnant. I had been dreadfully sick for weeks and my GP performed a raft of blood tests, including one for pregnancy; however, in his opinion, those extra hormones that indicate pregnancy wasn’t really high enough to suspect anything.
In the end, my GP decided that I had an ulcer that was causing the sickness, dizziness, and episodes of near fainting. So, by the time I grabbed a cheap pharmacy test, that very quickly showed those strong double lines, I was already almost 11-weeks pregnant.
Before I knew it, I was booked in to see an obstetrician who conducted an ultrasound in his office where he informed me that there was only one. I lay there thinking, well, what did you expect?
A week later, I was in the same office having another scan and this time the obstetrician had something different to say. This time I was told there were two. What a shock, after thinking two weeks earlier I may never have children, to wrapping my head around having one baby, to then being told I was having twins. I won’t repeat the reaction from my partner, but I started laughing and couldn’t stop. Of course, it wasn’t funny, I just think I was in shock.
The next step was to have an ultrasound by an actual imaging expert. The sonographer spent a very long time trying to find this thing called a membrane. It was clear the lack of this membrane was cause for concern, so I was referred to have another scan in two-weeks-time at the nearby tertiary hospital because they had a specialised high-risk pregnancy team. I still couldn’t understand why I might need to be under the care of such a team, however, my instinct kicked in and I demanded a referral from my private obstetrician even when he shrugged off the concerns of the specialist sonographer.
During that first scan at the hospital they still couldn’t find the membrane, but after a very long time and some close scrutiny of the images, a faint line was found, which meant my twins were
There were more scans in the following weeks and at just 20-weeks’ gestation, I was asked to wait in a small room while the sonographer checked the scan. She came back in not long after with one of the Professors from the GOLD team that manages high-risk pregnancies. He explained there was a serious growth issue with one of my twins and that I would have to stop working immediately. Twin-to-twin-transfusion-syndrome (TTTS) was suspected but so was selective intrauterine growth restriction (sIUGR). Either way, it didn’t look good.
Selective Intrauterine Growth Restriction
It turned out that the girls had sIUGR. We became accustomed to the sounds the machines made as the babies were examined every week on ultrasound. At just 24-weeks those sounds were very different and the room suddenly went silent. At this stage, they estimated the girls weighed only about 400 grams each. I was quickly jabbed with a dose of corticosteroids and taken to a private room in the maternity ward and told to rest because in 24-hours our babies would be delivered. I was visited by a team from the neonatal intensive care unit and the statistical chances of survival of both babies were explained – not much soaked in but I knew it wasn’t great.
“We became accustomed to the sounds the machines made as the babies were examined every week on ultrasound. But, at 24-weeks those sounds were very different and the room fell silent.”
It was explained that in some cases of sIUGR, following the steroid injection the condition of the growth restricted baby could stabilise. A follow-up scan would be conducted the following morning to see if that was the case for us. Needless to say, it was a long night.
When I was wheeled in for that follow-up scan everyone was holding their breath. The words from the sonographer were such a sweet sound, “It worked, your babies won’t be delivered today,” she said.
I spent the next week in hospital having daily scans and was allowed to go home if I promised not to do anything other than going to the hospital every second day for a scan. Of course, I did what I was told. But just three weeks after I was released from hospital those sounds coming out of the ultrasound machine changed again. We knew. The sonographer, who turned out to be one of the professors on the GOLD team, turned around and said, “It’s time, we have to get your babies out now.”
The girls were so tiny when they were born, Aasha weighed just 825 grams or 1.8 pounds and Bella was 1075 grams or 2.3 pounds. Aasha had chronic lung disease and a minor heart problem and they both suffered all of the usual issues premmies in NICU do. However, after 64-days in NICU, my little 28-weekers were well enough to come home.
Rebecca’s Story - DiDis
Rebecca Perrie is a fraternal twin, so when she was told she was expecting twins and they were also fraternal she didn’t question the diagnosis.
“My first one was heading towards two, and in my mind, she could play or be sitting at a table and I could be happily holding the other baby,”
“And when they told me I was having two, my whole plans for the future were not going the way I had envisaged,” says Rebecca.
She says that throughout her entire pregnancy there was never a mention that her twins could be identical.
“There was no doubt in their minds, all the sonographers and midwives, they told us all along they were fraternal twins,”
“There was no doubt in their minds, all the sonographers and midwives, they told us all along they were fraternal twins. So, we were very shocked at the birth when the paediatrician said to me that he would put his house on it that they were identical twins.”
“Even at the 19-week scan when we found out their gender and they were both girls, never once was it considered that they were identical,”
“So, we were very shocked at the birth when the paediatrician said to me that he would put his house on that they were identical twins,” Rebecca explains.
Rebecca and her husband Troy decided to have a DNA test done to establish if the girls were in fact identical. And, sure enough, they are.
The rate of identical twins is fixed across the world at 1-in-every 285 pregnancies and of those, just 1-per cent are the rarest type, which is Monochorionic Monoamniotic, or as they’re commonly referred to MoMos.
Jodie Wiren was just seven-weeks pregnant when she was told she was expecting twins, and that because of the type of twins she was carrying the road ahead wasn’t going to be smooth.
“What we didn’t expect was for the ultrasound technician to peer in closer and squint and really look at the screen even more,”
“And, then she ran out, didn’t say anything, just ran out,”
“Someone else came in and looked and went “ooooh”, that’s when we knew we had some trouble here,” says Jodie.
The close scrutiny of the screen and the “oohs” and “ahs” were the sonographers trying to find a membrane dividing the twins.
“They didn’t say a lot, they just said “they’re very close,”
“We waited for the report and we opened it up and the words just resonate with me forever,”
“Monochorionic Monoamniotic twins, viable pregnancy, a strong suspicion of being conjoined at the thoracic,” Jodie recalls.
“We waited for the report and we opened it up and the words just resonate with me forever, Monochorionic Monoamniotic twins, viable pregnancy, a strong suspicion of being conjoined at the thoracic.”
Both Jodie and her husband were convinced the twins wouldn’t be conjoined and they hung onto statistical data to keep their spirits up until they saw their Maternal-Fetal Medicine Specialist at 13-weeks. However, there was no new information and the next appointment was not for another seven weeks.
“We went back at 20-weeks and the babies were still alive,”
“And, he said let’s keep going until you get to viability, so 24 weeks,”
“At 26-weeks, I was going to the hospital three times a week and I went into the hospital to have inpatient care at 28-weeks,” Jodie says.
Jodie’s husband took three months off work to care for their two-year-old daughter while Jodie was in the hospital. The babies were born alive at 32-weeks’ gestation, with very knotted and tangled cords, but not conjoined.
As you’ve learned, there are certain types of multiples that pose higher risks during pregnancy and then there are some types that are almost as straightforward as carrying two singletons at the same time. That’s what Hypnobirthing Practitioner and Birthing Doula Elyse Jamieson from Somabirth found out when she discovered she was expecting twins.
As you’ve learned, there are certain types of multiples that pose higher risks during pregnancy, and then there are some types that are almost as straightforward as carrying two singletons at the same time. That’s what Hypnobirthing Practitioner and Birthing Doula Elyse Jamieson from Somabirth found out when she discovered she was expecting twins.
“My husband and I had been trying for another baby for a little while,
“I took my first pregnancy test and it had a very strong positive line straight away,”
“I had worked with a twin mum that year and she had said to me on one of my visits, ‘imagine if you ended up with twins next time’, and that little comment kept popping up into my brain,” says Elyse.
Elyse had decided that with this pregnancy she wasn’t going to have any medical intervention and was just going to ‘go with the flow’. However, as the weeks went by and she became quite sick she went to the doctor who referred her for an ultrasound.
“When I had my scan, sure enough, two little babies popped up on the monitor,”
“It did hit me like a bit of a curveball as I was hoping to prepare for a home birth this time around, but that was out of the question given the rural location that we live in,” explains Elyse.
“It did hit me like a bit of a curve ball, as I was hoping to prepare for a home birth this time around, but that was out of the question given the rural location that we live in.”
Elyse’s twins were DCDA or Dichorionic Diamniotic, which means they both had their own placenta and their own amniotic sacs. This is the most straightforward type of twin pregnancy. Even so, the hospital Elyse had planned to birth at had protocols that she wasn't happy with. In the end, after much research, Elyse found an experienced multiple birth obstetrician who was willing to work with her to achieve the birth she wanted.
Elyse's boys were delivered vaginally and breech, 12-minutes apart.
Choose Your Care Team Wisely
Whether your pregnancy is straightforward or fraught with complications, it’s important to be in the hands of people who are experienced with multiple births. And, remember, an identical twin pregnancy is very different from a non-identical twin pregnancy.
“It really is very different having an identical twin pregnancy to having a non-identical twin pregnancy.”
~Professor Craig Pennell~
Until next time...
I wish you Double Happiness ... Multiplied.
A zygote is a fertilised egg.
Fraternal twins are Dizygotic, which means two eggs have been fertilised by two sperm.
Monozygotic twins are where one egg is fertilised by one sperm and then that egg divides at some stage in the first two weeks after fertilisation.
You can get Dichorionic Diamniotic twins where some are identical and some are non-identical.
Monochorionic Diamniotic twins sharing a placenta are always identical.
The rate of identical twins is fixed across the world at 1-in-every 285 pregnancies.
Of those, just 1-per cent is the rarest type, which is Monochorionic Monoamniotic.
Monochorionic Monoamniotic twins are also identical, however, they share the same amniotic sac, which poses increased risks during pregnancy and requires significant monitoring.
Disclaimer: The content contained within this article is purely informative and educational in nature and should not be construed as medical advice. Please use the content only in consultation with an appropriately certified medical or healthcare professional.
Double Happiness Multiplied - What you need to know about having Twins, Triplets, & Quads book:
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Hypnobirthing Australia™ Practitioner & Doula, Soma Birth
Mono-Mono Twin Support Group
Helping Little Hands
Australian Multiple Birth Association
Perth & Districts Multiple Birth Association
Multiples of America
Twins & Multiple Births Association
The Multiple Births Foundation
Irish Multiple Births Association
Multiple Births Canada
International Council of Multiple Birth Organisations (ICOMBO)
South African Multiple Birth Association