are you on ovulation hormones ?
what I have been taught might be visible on the ultrasound , depending n the resolution I guess
I think it goes like this
1. there is di zygotic meaning two eggs and two sperms. then there has to be two placentas (dichironic) and two amniotic sacs (diamniotic) and the babies will not be identical because ther are two different eggs. because ther are two different eggs there is the same chanceofhaving either a boy or a girl as withany normal pregnancy . ie 50% chance that one will be a boy or a girl. so yes a 25% chance that they will both be of the same sex looking at the possible combinations
girl girl 25%
girl boy 25%
boy girl 25%
boy boy 25%
I had some friends when I was a kid who were di zygotous girls and it was very easy to tel them apart.
. . .
2. or monozygotic meaning that there is one egg and sperm that forms a cell mass (zygote) that splits
so if they are monozygotic twins then they have to identical
the number of sacs and placentas in the monozygotic twins depends on the stage that the egg cell clump splits at .
a) split Before day 3, the placentas are fused, but there wil be two placentas and two sacs (dichironic diamniotic)
b) split between day 3 and day 8 ( the blastocyst implants and the inner mass divides) so there is one placenta and two sacs , (monochorionic, diamniotic)
c) split between day 8 and day 13 results in one placenta and one sac, (mono chorionic, minoamniotic)
* reference: king Edward memorial hospital postgraduate training website 2012
so if you definately see just one placenta then they are identical. and if the placentas are fused, most likely identical.
if the placentas are located in totaly different parts of the uterus then probably nonidentical.
. . .
and I would expect that the chance of having an egg split (identical twins ) is less than the chance of having two eggs released which would be high if you are on ovulation hormones (non identical twins. )
. . I'm guessing that it might not be that easy to see if the placentas are fused or not in such a small space, I will leave that comment up to more experienced people on here Edited by studentDr - 12/9/12 at 9:39am