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Pamela Prindle Fierro

One Twin Bigger Than the Other

By May 7, 2007

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Many have marveled at this picture of Byron and Lincoln, identical twin brothers with dramatically differing birthweights. While their situation was likely the result of Twin-to-Twin Transfusion Syndrome (TTTS), size discrepancy in twin pregnancy can be a worrisome issues for parents. Thorn663 posted the following in the message forum... "I found out at 5 weeks that I'm pregnant with fraternal twins (first pregnancy). On the ultrasound, one gestational sac was significantly smaller than the other one. The MD said that the bigger twin looks great but he was unsure about the viability of the smaller one. I went back for another ultrasound today (6 weeks and 4 days pregnant). We saw two heartbeats, which was reassuring, however, the one twin is still about half the size of the other. Has anyone else had the same experience? If so, what was the outcome? I'm a bit nervous for the little one." Read the reassuring responses from other parents.
May 15, 2007 at 11:14 am
(1) Laura says:

Believe it or not 22 years ago we gave birth to identical twins and we did not know until delivery we were having twins. One weighed only 2/12 pounds and one weighed 4 1/2 pounds, it was quite a size difference when they were that small and everything went well! Good Luck!

July 27, 2007 at 6:03 pm
(2) Jackie says:

I am having the same problem right ow. I see you posted in may what was your outcome. Please email me vzes2920@verizon.net

September 9, 2008 at 4:25 pm
(3) Nichole says:

I just found out today I am having twins, and one is half the size of the other, there is a heartbeat but it’s unknown if the smaller one will make it. I’m trying to get more info on the chances that both will make it.

September 18, 2008 at 1:22 pm
(4) Catherine says:

I am having the same problem at the moment, I had an ultrasound at 5 wks 4 days where there were two sacs and in one they could identify a yolk sac etc and the other one they were not sure. They were telling me that it may have been miscarried already or that it is a vanishing twin. The other one is quite a bit smaller as well

March 6, 2009 at 11:15 am
(5) Cassie says:

This is exactly what is happening to me…..had an ultra sund and the gyno said that one is significantly bigger than the other….so he was unsure about the health of the smaller one…I am 6-7 weeks pregnant by the ultra sound….what was the outcome for you….please email me and let me know…thank you!!!!castarine.beharry@yahoo.com

May 6, 2009 at 10:36 pm
(6) Julie says:

Same thing happening to me! Am 7 weeks along, first baby looks great, second is about half the size. Both have strong heartbeats. But they’re having me come back for ultrasounds next week & the week after to monitor. Not sure what to think – am scared…..

June 26, 2009 at 11:41 am
(7) Brittany says:

I was told at 9 wks at my first ultrasound that i was pregnant with twins.. they only found one heartbeat. there fore they told me the second one died a day or two before the ultrasound because they were the same size.. what are the chances of the second heart beat being there when i go back ?? I cannot find any info on this topic at all..

August 4, 2009 at 12:34 pm
(8) Georgia says:

My daughter is pregnant with twins one is larger than the other but unable to get a good look at smaller twin and uable to see heart beat of smaller twin, I my self has twins 24 years ago and the smaller one did fine. Any advise.

April 19, 2010 at 3:39 am
(9) katy cairns says:

Hi, I had twin boys 9 march 2009 born 12 weeks early due to twin to twin- at birth fyn was 1 pound 6 and teddy 2 pound 8, they are now one and still teddy is nearly twice the size!! but they are both perfect x

July 14, 2010 at 12:53 pm
(10) mary says:

I just foud out 2 days a go that same case applies to me. The dr. said that 1 twin is normal while the other one is way too small and the twin is abnormal. He said that chances are the small twin will vanish. Iam only seven weeks and will have another sono in two weeks. Iam so scared. If anyone have any advice, please email me @ marymary0522@yahoo.com

August 13, 2010 at 6:05 pm
(11) Amy says:

I have been to my doctor 2 times so far in my pregnacy. I went last week for my first first at about 4 weeks. I have a history of miscarriage so they needed me in ASAP. I ultrasound looked good for only how far i was.
I went back yesterday for another untrasound. And there was TWO sacs. One quite larger then then the other, is this normal for twins?

March 15, 2011 at 12:50 am
(12) Liezl says:

I went to the doctor last week at 5 weeks pregnant, he did an external ultrasound and I was told there were two sacs (twins). I went again yesterday to a clinic and had both an internal and external ultrasound. The lady operating the ultrasound could only see one sac. I then went to my doctor because I was confused, and he could still see two, but one sac is suddenly much bigger than the other. The doctor says that it looks like the smaller one is going to vanish, and that only the large one will be viable. What happened to all the other ladies in this discussion that were in a similar situation? Did both twins make it? And I still don’t understand why an internal ultrasound didnt pick up 2 sacs, while the external one did?!

April 27, 2011 at 3:49 pm
(13) Charnay says:

Hello Im currently 6 weeks and 5 days i went to get a ultrasound a few days ago and i got the print out of two sacs one had a heart beat the one thats 6 weeksa and 3 days the other was a week behind. it hasnt been confirmed of twins yet but is it ok for a twin to be a week smaller?!?

November 10, 2011 at 1:20 pm
(14) Gemma says:

I found out I was having twins at 13 weeks and one baby was 5 days smaller than the other. By 28 weeks they were the same size and at birth (36 weeks) they were 7lb 9oz and 7lb 10oz.. now the ‘smaller’ twin at 18 months is about 5lb heavier!

August 19, 2012 at 1:05 am
(15) crystal says:

The same thing is going on with me now. I’m 6 wks 4days pregnant with twins. I had my second ultrasound and saw 2 strong heartbeats but one sac is bigger than the other. My doc said I could be losing amniotic fluid in the smaller sac. He want to check when I get 8 wks to see if the small sac has gotten bigger and if not will give me an antibiotic to help the sac heal and get that sac growing. He didn’t sound like any of this was something to worry about so I’m good.

January 12, 2013 at 8:09 pm
(16) kay says:

found out im having twins an they heart beats sounded good but one baby was way smaller then the other like half the size really scared an not sure whats gunna happen any advice or anyone been through this that know the outcome?

February 12, 2013 at 11:01 am
(17) Marisa says:

Dr found two sacs at 5 weeks. At seven weeks one twin measured at 6 weeks 2 days other twin measured good at 7 weeks 2 days. Dr didnt give an answer as to what will happen, that she see’s so many things. So my question in people in same situation, what eventually happened. Did one twin vanish or did they make it out okay? Thanks

May 25, 2013 at 2:05 am
(18) cass says:

I had sex and then started to bleed brown blood i went for utersound and the docter said the baby is healthy but he could see another sac on the other side but no baby could i be having twins im 7 weeks and 6 days..

August 21, 2013 at 2:39 pm
(19) Brittany says:

I just found out I’m having twins. I’m scared but one twin is 14 weeks & my other twin is 12 weeks so is this normal I’m scared..

April 1, 2014 at 10:22 pm
(20) Hannah Clarkson says:

I went in for u/s at 7 weeks after having ivf and 2 embryos transferred. They confirmed it was twins but one twin was about a week behind. Twin A had a heart rate of 147 and twin B had a heart rate of 106. The doctor seemed really concerned and wanted to book a follow up u/s 2weeks later. She printed a picture of Twin A but not one of twin B. That pretty much freaked me out and confirmed to me that she didnt think twin B would survive. Ive been extremely ill with nasea and vomitting the last few weeks and wondered if that could be why twin B wasnt getting enough nutrition cause I couldnt keep much down. I researched and with twin pregnancies you need at least 600 more calories per day compared to your normal intake pre-pregnancy, and your protein intake should be higher (anywhere from 90-120 mg daily). Now that im feeling better I am trying to take in more nutrition and will hopefully see if it helped with my next u/s. I will try to keep everyone updated as the other posts did not. Hopefully I can provide some answers to the worrying mothers out there. I understand and know it can be horrible. I wont know for just under 2 more weeks. For the other posts…..please let.us know what happened to the smaller twin…good or bad.

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