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Robin Elise Weiss, LCCE

Fraternal Twins Share a Single Placenta

By July 12, 2003

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Until just recently it was thought that all fraternal or dizygotic twins must have separate placentas, since they come from separate eggs. However, this week in the New England Journal of Medicine it was reported that a through investigation of fraternal twins born with what was believed to be a single placenta was indeed accurate. It is extremely rare for this to happen, and there is only one other report in medical literature. It is believed that the most recent case is due to the use of in vitro fertilization.

I wonder if it could have also been a case of fused placentas or something like this section: Twin Placentas

Your thoughts?


March 19, 2007 at 10:28 pm
(1) cynthia can says:

I just wanted to get in touch with someone who cared to know that I had fraternal twins natually & they shared the same placenta. They were born Nov. 4, 1978 at Marrietta Hospital, in Marrietta, Ohio. Dr. Carmen was the attending physician. I have pictures of the birth & placenta, etc. I never understood why they shared the same placenta when they were definately fraternal boys. They are now 28 years old. I really hope a scientist will contact me because I never knew how unusual this was & never really understood why this happened.
Well, I hope whoever reads this will forward it to the right professional.
I live in Richmond, VA.
Thank you, Cynthia Cain

October 29, 2007 at 9:03 pm
(2) Alba says:

Im pregnant with fraternal (boy and girl)twins in a single placenta and two amniotic sacs. It was the strangest thing I heard when they told me so. I looked it up on the internet and also found out it was the most uncommon thing. Although Im really happy to have my children soon, I would like to know how this is so?

May 23, 2008 at 10:04 pm
(3) Thais Frost says:

I gave birth to twin girls just this past March 2008- conceived naturally. They shared a placenta, but they are definitely not identical! Perhaps this is not as uncommon as everyone thought.

July 16, 2008 at 3:43 pm
(4) Judy Easley says:

In 1978, I gave birth to fraternal twins, boy and girl. At birth, there was an unexpected complication. I was told the girl (smallest baby) had taken the boy’s blood. He had to have a blood tranfusion, was anemic and remained in the hospital for a week. The girl came home with me within 2 days. However, I was never given a medical name of the condition. After researching, I can only find informaion on Twin-to-twin Trasfusion Sydrome (TTTS). But I’m not sure if this is possible because they are fraternal twins, and the only information I’ve found is that TTTS occurs only with indentical twins.

Can someone verify that TTTS can occur with fraternal twins or perhaps their is another medical term I should be researching.

The twins are nearly 30 years old and the hosital cannot provide their birth files.

Any information would be appreciated. Thanks.

August 2, 2008 at 7:54 pm
(5) Sue Foster says:

I had twin fraternal girls in 1978 who shared a placenta. Immediately upon their birth, I was told they were “identical” and questioned the doctor because they looked nothing alike. Both redheads, different colors, one with blue eyes, one with green, different blood types. He stated there was only one placenta, and his head nurse verified his findings. Can this be explained? Now they are 29-years-old, one is 5’4″, one is 5’8″, one with auburn hair green eyes, one with copper red hair blue eyes. Definitely not identical! I’m interested to find out how rare this really is.


August 5, 2008 at 8:48 pm
(6) Jeanette Bisesi says:

I was unaware that this was uncommon. I am 20 wks pregnant with boy/girl twins that share the same placenta. My Dr. did not seem at all surprised that they share they same placenta. I found this website only because I was trying to find out why they would share a placenta. I conceived naturally with no IVF.

August 5, 2008 at 8:52 pm
(7) pregnancy says:

They most likely have a placenta that has grown together due to lack of space in the uterus, which is a separate issue. To my knowledge the case reported on here, is the only one known. If you think yours is another one – I’d have it tested after birth to see if it’s simply fused or separate placentas.

Good luck! My twins are 5 and a delight!


August 8, 2008 at 9:31 pm
(8) Jane says:

I gave birth in 1970 to a set of twins (girl and boy). I was told by my doctor that there was only one placenta. This man had delivered hundreds of babies prior to mine and didn’t seem surprised. Also interesting, no one had a clue I was having twins until after the first one was delivered and my stomach didn’t go down.

September 13, 2008 at 1:11 pm
(9) Jenny says:

I am a twin born in 1976 in Pennsylvania. My fraternal twin sister (I’m female too) and I shared a single placenta. The doctors told my parents that it was very rare.

October 26, 2008 at 11:31 pm
(10) jennifer says:

I too gave birth to fraternal twin girls on september 20, 1994. They shared a placenta and the doctor who had delivered thousands of babies said that we would have to send the placenta out for extensive testing to see if they were identical. All he had to do was look at them, one had a beautiful head of wavy dirty blonde hair and the other was very light blonde peach fuzz!!! A few hours after pushing those babies out, i shuffled to the nursery and a woman stood at the glass and said “i heard there were twins born today, but none of these babies look alike!” What a surprise, reports came back and said they were Fraternal. they are now 14 and the only thing they share is their eyes! one is a blonde who tans beautifully, the other is a red head with freckles and very irish skin! One is 5ft 8in. and the other 5ft 4in and there is about about a 20lb difference in their bodies, though both can wear a bikini, one is bones and the other has broad back and shoulders. OH, AND HERES THE KICKER, ONE OF THEM WAS DIAGNOSED WITH TYPE ONE DIABETES AT AGE 4 and is insulin dependant!
Anyway, the reason for the sudden interest is that my girls are taking Biology in high school and their teacher told them it is EXTREMELY rare to be fraternal twins who shared a placenta! after reading everyone’s posts, i am thinking that bio teacher might be wrong!

December 20, 2008 at 11:42 am
(11) lizz says:

My fraternal twins shared a placenta. Didnt think this was rare.

December 21, 2008 at 10:17 pm
(12) sandy says:

I had twin girls in 2004, they had seperate sacs and one placenta. they dr told me he would have to send the placenta for testing to see if they were identical (financially I chose not to do that)they look identical to everyone, i can tell the difference though. I was told that they were probably not identical because one has a flat mole on her inner thigh & that both would have it if they were identical does anyone know if that’s true.

January 31, 2009 at 7:19 pm
(13) twin from nj says:

I am a fraternat twin (boy/girl) im the girl i have been looking for information about this for years now!!! I am 23 when my mother had us she was also told that is was rare..Today what the first time i found any kind of infomation on this… I feel the same way. How come back in 2003 they were the first and finding all the commonts going back from the 70′s it doesn’t make any sense. I would like to know more about this. If anyone has any infomation on it i would like to know thank you. For all your help.

March 23, 2009 at 12:50 am
(14) Stephanie says:

Wow! I never realized this was supposed to be such a rare condition either. My twins (girl/girl) were premature, had TTTS, and I was also told they had the single placenta. In fact, because of some other birth anomalies, the doctor said he would need to check their chromosomes to verify that they were, in fact, not identical. This was because they had been presumed to be fraternal before; however, they were apparently mimicking identical twins with their illnesses. Needless to say, they are fine now. (They were born in ’98.) I never would have thought the single placenta was supposed to be so rare, since no one seemed to pay it any attention at first. Go figure!

May 9, 2009 at 12:43 pm
(15) kay says:

I’m almost 19 wks and started looking into this when I was told my twins had same placenta and two sacs. One is def a boy, the other seems most likely a girl. Their sonogram pictures look nothing alike to me. Besides the sonogram chick makin sure they were both developing normal they acted like it was no big deal. Must be more normal these days.

May 13, 2009 at 10:38 am
(16) Alyson says:

Hi – I’m a twin born in 1970. I (female) have a twin brother. My mom says we shared a placenta and the doctor had it sent out for tests and never heard anything. I (2nd twin born) was a surprise to the doctors because my Mom’s labor stopped after my brother was born. The palcenta was delivered…and there I was. I asked my OB about this when I was pregnant and she did not seem surprised either. I’d like to see more information on this topic and what the complications could be.

May 13, 2009 at 11:07 am
(17) pregnancy says:

I think it’s also important to note that many people are told that there was one placenta, this is because there is only so much surface area in the uterus and two placentas frequently meet and grow together. This is not the same thing as only having one placenta. The example above can only be determined via testing. And the case in the blog post was the second time it had been noted, ever.

September 30, 2009 at 10:44 pm
(18) tammie says:

i had fraternal twins on feb. 28th 1987 my girls are now 22 years old and when they were born i was told that they were in their own sacks but shared one placenta they look nothing alike one has brown eyes and brown hair the other has blue eyes and lighter hair one is 5’6 the other is 5’9 when they were born i remember seeing the placenta which looked like the umbilical cord started out as one and then “y” were the placentas fused?

January 21, 2010 at 9:05 pm
(19) Traci says:

I wanted to know more information about this condition. I am currently pregnant with twin girls who are sharing one placenta,but are in different sacs. Someone told me that this meant they were identical and wanted to know if this was true.

April 5, 2010 at 11:19 pm
(20) Sujatha says:

My fraternal twins (boy and girl) born in 1993 had sac separation but shared a placenta.

August 27, 2010 at 6:43 pm
(21) Earlene Nuzzo says:

I’ve read all the comments herein and conclude it is rare that fraternal twins share only one placenta. However, my fraternal twins are probably the rarest of all. They (bitg boys) were born and the doctor was shocked as he discovered they were fraterbak abd shared only one placenta as well; however, even more shocking is that they have different blood types. Dr. stated he had delivered over a thousand babies and had never come across this before. Scientists still haven’t figured it out after all these years and are puzzled how this could be….a miracle. They were born Aug. 27, 1963, and are 47 yrs. old today. We were hit by a drunk driver on my way to the hospital and because my Dr. had 3 patients to take care of, plus the delivery of my twins, he did not document their birth, otherwise they would have been in the Medical Journals of Medicine. Dr. was Paul E. Travis, from Downey, CA and they were born at Mission Hospital in Huntington Park, CA. I do wish someone could look into this as I don’t know how long a doctor is required to save medical records.

August 28, 2010 at 5:23 pm
(22) Tyi Jones says:

I just recently gave birth to fraternal twins which were sharing one placenta. Through out the whole pregnancy we were expecting identical girls. The doctors and technician identified the babies as dizygomatic. i did not undergo any treatments or took fertility drugs. This was natural.

October 1, 2010 at 7:09 pm
(23) GRAHAM SMITH says:


October 25, 2010 at 7:27 pm
(24) jennifer says:

I gave birth June 4, 2009 to healthy twin girls. There was only one placenta and it was tested to see if there were 2 that fused together. The entire pregnancy the ultra sound tech told me they are identical. I had DNA testing done by a cheek swab and the results are that my girl are fraternal. I am a fraternal twin as well and I conceived naturally. From all the comments I have read it doesnt seem that rare to have fraternal twins with only one placenta.

March 3, 2011 at 10:58 pm
(25) Nakia says:

I gave birth to twins on 10/10/ 2002 in Michigan. Both girls, one placenta. When I went to the recovery room and got my first look at them they were night and day and they still are. What kind of identical twins do I have ?

March 15, 2011 at 5:23 pm
(26) jane gregory says:

I have twins boy girl with one placenta the doctors induced me at 35 weeks because they had twin to twin syndrome. the doctor told me that one of the babies was eating all the nutrients and the other had stopped growing. since then i have been told that only identical twins can get twin to twin syndrome. this was in 1995 so how can this be possible. also as far as i remember there was only one sac.

April 2, 2011 at 6:12 am
(27) You says:

As far as I have researched and to the best of my knowledge, fraternal twins cannot share the same placenta, but the placenta can become fused together to appear as one placenta. Enough said. The author says that there are no other reported medical evidence of fraternal twins sharing placenta, yet all of you think you are some undocumented exception. Silly.

April 25, 2011 at 5:29 pm
(28) koalabear says:

My brother and I are twins and we also shared the same placenta. Mom was told this was rare too. We’re 33 years old, born in Peru, and we were born 5 minutes apart.

April 25, 2011 at 5:35 pm
(29) koalabear says:

To add to my previous comment, my brother and I were born with both of our legs wrapped around each other’s necks. Mom had to have a C section.

May 9, 2011 at 11:46 am
(30) jessly says:

My brother and sister are Fraternal twins born with one placenta. As babies they looked very in common but as adults ( now 28 yrs old) they have nothing in common. but they are from the same placenta and the doctor told my mother that this was very rare but it does happen.

July 9, 2011 at 9:00 am
(31) Nikki says:

Hi I had fraternal twin girls in 2005 and they shared a placenta too. They were in separate sacs and I was told that the placentas fused together to form one. I thought that was the bodies way of conserving energy and was very clever. Did not know it was rare but after reading these comments I don’t think it is :) My girls were conceived naturally too.

July 9, 2011 at 9:32 am
(32) Robin Elise Weiss says:


A fused placenta is different from this case. In your case, there simply wasn’t enough uterine space for the placentas to live apart and they eventually met and grew together. The case in this study was ONE placenta from the start and it is one of only two known/proven cases in the scientific community.

I had identical twin girls who had two placentas from the first ultrasound, but at birth, theirs had also grown together. Without looking with a microscope, this can be hard to tell. Now, early ultrasound can help shed light on whether it’s a single placenta or not because we look very early on.


July 9, 2011 at 9:46 am
(33) Nikki says:

Thanks Robin I assumed what happened to me was common as it makes sense for the body to do that.
Even though my girls were in separate sacs from the beginning and the placenta was shared from the first 6 week scan we were told when they were born to get a test to see if they were identical as they shared the same blood type.

We never bothered as it was pretty obvious they were fraternal as they look nothing alike :)

August 22, 2011 at 2:12 pm
(34) obafemi says:

my wife just delivered our first babies-
a set of twins (boy & girl) july 2011 and they both shared a placenta. i did not know anything unusual about this until my cousin visited us and said this is the eighth wonder in the world. if so, it is surely an act of God or what is this scientifically?

September 20, 2011 at 4:49 pm
(35) Tina M says:

It is interesting to see that these number of people have had
the same experience. I had twins too (2010) boy/girl and they shared a single placenta. i remember the Nurse expressing wonder at such a happening. Eventually, her conclusion is that science cannot explain God’s work.

October 18, 2011 at 2:17 am
(36) TLK says:

im 20weeks with twins who share the same placenta n i have heard so many bad story’s but then after reading all these i feel so much better i was starting to worry more than i should have

November 16, 2011 at 2:31 pm
(37) VidaD says:

I also had fraternal twins naturally conceived and they shared 1 placenta. I was also told at birth that it was very rare and the dr.’s offered to send the placenta for testing. My boys are now almost 10 years old, they look and act NOTHING alike. One is exceptionally smart and the other has a learning disability. All that really matters is that they are healthy who care what scientist and doctors have to say its not like the results will change who the children are and we all know they aren’t always correct.

November 18, 2011 at 8:24 am
(38) jane daly says:

I am 22 years old and a fraternal twin, my mother was told by her doctor at about 4 months that our placentas had fused together. When we were born the doctor said we were identical because only one placenta was delivered. But we looked nothing alike then and still don’t now.
Im brunette and heavy and dark skinned and always have been, she is blonde, thin and pale skinned.
Her bone structure is smaller than mine. She weighed more than me at birth too almost a pound more.
So how come doctors are only ”discovering” this now???
Our local doctor in a small town in Ireland witnessed it over 22 years ago and at our birth my mother informed the doctor that we were not identical…..
I was wondering how rare it was though.

December 18, 2011 at 11:21 pm
(39) MKG says:

I gave birth to fraternal twin boys in 2004. When they were born the doctor told me they were identical and shared one placenta. The doctor examined it and verified it was only one and not two fuzed. My boys are definately not identical twins. They have different hair color and look different. One also has a speech disorder and some learning disabilites. The other one does not. I would love to know about this. I’ve always wondered. We’ve never had them genetically tested but I know they are not identical twins. They were naturally occurring also.

January 10, 2012 at 6:36 pm
(40) Karenmc says:

My grandmother always took great pride in telling everyone the story that my dad and his fraternal twin sister were of the same placenta. It was so rare that a professor (not sure of his speciality) came to see her in hospital. This was back in 1943!!! My grandmother also complained frequently that her tummy never recovered and likened it to a set of Venetian blinds.
Unfortunately my dad’s twin sister passed away in November 2011 one week before their 68th birthday. This is why I’ve started to investigate it because people said it phenomenon was impossible. Clearly it isn’t!!

March 5, 2012 at 10:55 am
(41) hippiegypsy says:

I was baffled at first when during my many ultrasounds the doctor told me i was having identical boys since there was one placenta. then they were born. nope, not identical. but the whole time there was ONE placenta. i was kind of bummed. i thought there were going to be identical. oh well!

June 20, 2012 at 8:10 pm
(42) ber says:

Its apparently becoming more common because I gave birth to two naturally concieved fraternal girls 5 days ago and the Dr said there was only one placenta. They should start keeping a more up to date tally on this.

June 20, 2012 at 11:57 pm
(43) pregnancy says:

My hypothesis is that there really isn’t an increase in fraternal twins with a true single placenta, rather an increase in physicians throwing the words single placenta around to merely indicate two placentas that started out separate and grew together or two placentas that started out at the same juncture making it visually indistinguishable. I’d go back, if your birth was recent, and ask what the pathologist had to say about the placentas. Also, go back to early ultrasounds, lots of times that will show two separate placentas. See, eventually the uterus runs out of room to house the placentas surface area wise. The other option is that your girls aren’t really fraternal. Without DNA testing it can be really hard to tell, even in cases of IVF where two embryos were put back into the uterus.

I find the whole subject fascinating! Good luck with your twins – it is so worth it!

August 10, 2012 at 6:28 pm
(44) Penny says:

Identical twins are not always single placenta either. If the embryo takes up to a week to split they will tend to form a single placenta. If the embryo splits within the first few days of conception you’ll have two placenta but identical twins. Does anybody know if they have given a name for this actual one placenta two sacs phenomenon? I can’t find anything.

August 26, 2012 at 3:55 am
(45) One of the Twins says:

@Penny, Wikipedia does not yet have a name for this condition. You can suggest a page be created for it, but it may be hard to find a contributor to the project who is also a taxonomist (someone qualified to make up words).

@Robin, the author of this article, my thought is that the only other documented case besides the in vitro fertilization case of this unnamed phenomena was also a case of fused placenta. So, only one case, the one with in vitro fertilization, is the only actual single, non-fused placenta of fraternal twins. Therefore, the only way to get fraternal twins to share a single placenta from the very start is to artificially fertilize the eggs. And the only way to get this phenomenon naturally is through fused placentas.

August 26, 2012 at 7:53 pm
(46) pregnancy says:

@One of the Twins: I’m in complete agreement with you about the fused placenta versus the one case of this we’ve see that is documented. I think it’s mostly a misunderstanding of how it works.

September 30, 2012 at 10:14 pm
(47) Elizabeth says:

My mother would have had a fraternal set of twin boys, one twin disappeared. 6 years later she had my fraternal twin sister and I (1973)…. Our Placenta’s fused. Two years later she would have had a set of triplets…but one triplet disappeared. Two years later she had a single birth. Basically, she would have had 2 sets of twins and 1 set of triplets and a single. I just find it interesting that the placentia’s fused together.

November 27, 2012 at 2:39 pm
(48) Stephanie says:

I had them in 1991. They are boys, fraternal and yes they shared one placenta.They were naturally concieved. I remember the Doctor letting me that they would have to send the placenta out for testing because it was definitely obvious that they were not identical. The look very different. I never heard back from the Dr. but I often wondered how that came about. He did say it was uncommon.

March 7, 2013 at 10:57 am
(49) Loretta says:

I just found out after 50 + years that my sister and I are fraternal twins. However, my mother insists we came from one placenta and that we are identical twins. My twin is 5′ 11″ and i am 5′ 3″ , she had dark hair and I had light hair. My mother may be right with this explanation. This explains why their was one placenta, but the DNA test confirms we are fraternal. Thank you I will forward to my mother.

December 1, 2013 at 12:14 pm
(50) Kelli says:

I am a fraternal twin born from one placenta. :) Born in 1980s boy/girl twins. I’ve been told that our internal genetic makeup is identical. If I ever need a transplant of any type I can get it from my twin.

February 18, 2014 at 5:17 am
(51) mandy says:

My brother and I are fraternal twins turning 40 years old soon. According to my mom we were born with one placenta (4 blood vessels instead of the usual 3). We were born in 1974 so no such things as scans existed then …. we were a big surprise to my dad!

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