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I thought two placentas meant fraternal twins

post #1 of 10
Thread Starter 
I need to go get that book that people keep reccomending to me and learn about twins! I just found out I'm having twin girls. They each have their own sac and own placenta, so I just assumed they were fraternal. So, they could be identical eh?

I have so much to learn in the next few weeks.
post #2 of 10


No, to all my understanding two placentas definitely means fraternal. ( I have twin boys 2 1/2) congratulations, you are in for one wild ride!!

post #3 of 10
My sister has identical boys and they each had their own placenta and sac. (She had their dna tested.)
post #4 of 10
Welcome to the twins club!

I thought two placentas = fraternal but, I could be wrong.
post #5 of 10
Nope, MZ twins can (and about 1/4 do) have separate placentas. It all depends on when the egg divides. If the split happens pre-implantation, they will have separate placentas. If the split happens post-implantation, they will share a placenta but may or may not share a sac, depending on when the split occurs.

The only surefire way to know that twins are MZ are if they definitely share a sac, or they share a placenta that you can tell isn't just fused.

The only surefire way to know that twins are DZ (fraternal) is if they are a boy and a girl.

Same sex twins that have separate placentas are impossible to know for sure without a genetic test.
post #6 of 10
Thread Starter 
Thanks for helping me clear that up everyone! I guess we won't know for sure unless we get a DNA test.
post #7 of 10
Mine are identical and they had seperate placentas and sacs. I think one of the u/s techs even told me they were not mz because of that, but we had them tested and they are! Having Twins by Elizabeth Noble was the book I liked best about twins, she is very into natural and home birth and nursing and everything.
post #8 of 10
Originally Posted by Tigerchild
The The only surefire way to know that twins are DZ (fraternal) is if they are a boy and a girl.
I have read there is a very rare chance of MZ boy/girl twins. In this case, the fertilized egg is XY, but when it splits, one twin loses the Y chromosome, and is left with only an X chromosome, which is a girl. this is known as Turner's Syndrome, which can occur in singletons too. There are only 3 known cases. Here is one place that describes it:


Just to add to the confusion .
post #9 of 10
Whether identical babies share a physical connection (conjoined twins) the amniotic sac, a placenta or whether they have their own sacs and placentas has to do with when the embryo split into two pieces. The later the split the more they share. This all occurs before 10 days post conception.
post #10 of 10
Hey Lindsay! Congratulations!! What a shock huh? Too say the least!! I have twin girls too. My son was not quite 18 mos when the girls were born. So we are in similar boats. Hard to imagine 3 so close huh?

But yes as a poster said 2 placentas can defintely be EITHER id or frat. I am always amazed at the amount of moms who said their doctor told them it was frat because there are 2 placentas. It irritates me that a doctor gives out that kind of wrong information!! 1/3 of those babies are actually MZ twins!! That is a big percentage! So if their blood types are the same then go on to DNA tests if you want to know.

My girls are MZ but there was only 1 placenta. We didn't know for sure till they were born because there is always that chance that it was orignially 2 placentas that fused into one. But once it was examined after birth it was definitely one.

I wanted to tell you though that there are a few of us that have gotten preg with our MZ twins while nursing. I was suprised myself to know I was preg with one more or less two because I was nursing ds so much and only had 2 (sort of) periods. Karen (1plus2) I know had the same situation and she shared with me something she read about being low on calcium while nursing which may cause the egg to split. Interesting huh?

Good luck to you girl!! By the way I checked out your blog and saw your pics of you huge belly!! Man that brings back memories!!! It is amazing what your body can do!! Hang in there!
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