Fraternal twins different ages?

missfire

I keep getting this question, and I'm not sure how to answer it. If it comes up in conversation that our fraternal twins are different sizes so far, the person will say to me "Maybe one is just younger than the other. I saw a documentary about that."

Even the MFM, when I dared to ask, just shrugged and said "Oh, who knows - there was that documentary about it, so perhaps."

Is this actually possible, and what documentary are they talking about?

I always thought they would have been conceived the same day, but now I'm second-guessing what I know about when an egg can be fertilized and when they would have implanted. Could it be a few days different? More?

Thanks! I feel dumb even asking, but I'll feel better to know where to look for an answer!

macchiatto

Fraternal twins can sometimes be conceived at separate times but I think it's usually when the mother releases two eggs within a 24-hr period, so it's not a notable "age difference." I think there have been a few cases where conception occurred farther apart than that but it's one of those things that's so rare I wouldn't think much of it unless there is compelling evidence to suggest it.

MADforever2009

Yeah they say it is possible... At an early week i was told baby B was measuring 3 days OLDER than baby A.  I've been told as far as hyper-ovulation goes it is possible that you could not drop two eggs at the exact same time and yes, they could be fertilized a couple days apart. (Sperm can live for days inside.)  That's why its possible to have fraternal twins by different dads.  (rare but possible.)

Now as far as my pg goes...both babies now are pretty much same size... 

macchiatto

Btw, it is pretty common for twins to measure a few days apart since different babies grow at different rates. My boys often measured anywhere from 1 to 5 days apart but sometimes they measured exactly the same. At birth, their size difference was 3 oz and 1/4 of an inch.

ewiley28

No answer, but I've totally wondered this too! Our "A" measured 3 to I think as much as 5 days older than "B" for the first few sonograms and so in my mind she is "older" than her brother.  But, as of the 20 week ultrasound he actually outweighed her by an ounce. 

I'm guessing the answer is we can never really know if the eggs released at approximately the same time or if they were actually a couple days apart.  I think both are included within the term superfecundation?  

Oh, the other thing I remember being told was that since they had a consistent size difference at 6 and 8 weeks, it was highly likely that they were fraternal rather than being one of that 30% of identicals with two sacs.  And ours definitely are fraternal (boy and girl).

aprilsarahjune

I saw the documentary ... it is about a woman in the UK who was a few months pregnant with a singleton.  For some medical reason, she continued to ovulate and a second egg was fertilized.  There were a lot of medical complications.  The odds of this happening are so slim that it is not worth worrying about ... and it was apparent during her pregnancy that they were different gestational ages.

ppants

My twins are boy/girl and he's always been bigger than her.

I do think my twins were conceived on different days.  I was charting and thought I had O'd since I had a temp dip and then it was higher a couple of days and dipped again.  Not that it really matters either way though.