Size differences in MZ twins at birth and later

nak

i don't have twins, but i am one. i was 3lbs 8oz and J was 4 lbs 12 oz. she was also about an inch longer. we were 41 weekers, healthy, no ttts. now at nearly 30 she's still about 1/2 inch taller and usually weighs a bit more than i do. my dad used to joke that she just got 3/4 off the egg

i've always been curious as to the size difference myself.

TTTS is not about weight differences or size differences (though obviously, those are "markers" because they are the effects of one twin donating blood to the other).

Unless your kiddos had vein-artery connections in the placenta, they did not have TTTS (which is formally diagnosed by certain bloodflow patterns detectable in US or upon examination of the placenta--size differences can tip off a doc to then take a look at the bloodflow pattern, but they do not diagnose TTTS). They *could* however, have had unequal shares of the placenta (a 55/44 split, say, or even higher, though it's believe that a baby MUST have at least 25-30 percent of the placenta to survive). It is possible to have one MZ twin have IUGR and the other one not, due to placental issues.

TTTS is a placental issue, but a very specific one. If you were being watched for it, and if they took your placenta to the lab for analysis/inspection, then the information should be in your file. Otherwise, it's probably safer to assume that the size difference probably is due to placental share independent of TTTS.

If you're curious, ask to see your file. Most doctors do at least a surface exam of the placenta, and will note where the cords are placed, ect. Probably your smaller twin had her cord placed in a slightly off spot, which would account for her accessing a smaller amount of the placenta. But TTTS is something very specific and different. Not saying your twins couldn't have had it, but less than a lb difference at birth is pretty mild for TTTS babies.

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This is just the kind of information I was looking for. Thank you for your post

They did look at the placenta in the lab and confirmed the mono/di and my doc never mentioned anything about TTTS, so I figured the weight difference was just part of who they were. But I will ask about where their cords were positioned -- that would be interesting to know.

I'll be curious to see if the weight difference continues throughout their lives. Ah, one of the many joys of twins -- watching to see who they become and what their "twinness" means. Thanks again!

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My boys were almost 2 lbs apart at birth, and about 2 inches different in length. They've stayed 2 lbs apart (though the bigger they get, the less it's noticable...it's not really apparent now unless you pick them up). Dylan is only about 1 inch shorter now.

My boys looked VERY different at birth. Because of the weight differences and some IUGR from both cord placement and TTTS, Dylan *looked* like a preemie. Tom didn't at all! My body made extra rich preemie milk for a long time for Dylan, and Tom really porked up on it (it was pretty funny). Now they look so much alike in photos (they have very different facial expressions, and personalities, so once people get to know them they can tell them apart easily) that sometimes I have to write down who was wearing what or ask them to identify themselves.

I will see if I can dig up some photos of the progression if people want, and post it in an edit. But don't worry if your babies don't look a lot alike. There are MZ twins that look very different, but chances are even if they don't look alike now they'll "grow into" it. I think you get the most comments about 'looking alike' when they're babies though, because to some people (myself included, unfortunately) most babies look more alike than different.

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Would you believe in our case the colors were reversed? It totally freaked out the doctor. I don't know why Dylan (our donor) was so colorful at birth (later he just turned yellowish/orangish red from jaundice). The pics we have of them at a week old it's REALLY noticeable.

Of course, we found out later (within a day of bringing them home) that Tom was just pale because he'd picked up a staph infection in the hopsital and it had gotten into his bones.

But D was all wrinkly and little old man-like! I'd totally forgotten about thinking that.

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This is our case as well. My girls were monochorionic/diamniotic and I was monitored closely too. Baby #1 (she was Baby B, but was born first) was 4 lbs., 3.8 oz. Baby #2 as 4 lbs., 12.4 oz. They were born at 32 weeks, 6 days. The size difference wasn't significant, but Baby 1, the smaller baby, was very pale for a long time as an infant. I always wondered if a little bit of TTTS did occur and they just didn't note it.

They're 3.5 now and they weigh the exact same most of the time, but one is about 1/2 inch taller than the other. Funnily enough, it's the smaller baby who is taller. Up until about 6 months ago, the larger baby was always a pound more than her sister, but her sis has caught up with her in the weight department. It will be interesting to see how they grow as they get older.