Thursday, Jan. 18 at 8 pm and 11 pm, and Saturday Jan. 20 at 7 pm, National Geographic Channel is (re?) airing the special "In the Womb: Multiples". The short video is at that link, while the description is here:

Egg and sperm meet and spark a perilous journey of fetal development, but what if there are two, three or even four along for the ride? In the Womb: Multiples, a two-hour world premiere special, utilizes groundbreaking technology to take viewers into the extraordinary world of twins, triplets and quadruplets as they develop in utero. The special follows the stories of three expectant mothers from conception to birth and travels inside the womb to see the tiny fetuses begin to interact with each other.

My understanding is that this special will air some of the most incredible 4-D ultrasound of triplets in the womb that has yet to be seen. The trips are reportedly shown being rather playful with each other, holding hands, yanking on each other's umbilical cords. You know: sib rivalry and personalities being displayed in all their glory and all that kid stuff.

The video on the website doesn't include that part. I wonder if it's on YouTube or will be....

...Well, the short promo is, and it gives a very good preview in only 14 seconds:
"