first ultrasound - We saw the gestational sac of both embryos, with the yolk sac of one clearly and the other yolk sac was almost imperceptible.
The one was larger than the other, they were not sure if the smaller one was growing or not but they told us we needed the second ultrasound (US) to really have a baseline comparison for growth. That would come in a week or so.
They said the larger of the two was perfect in size and they were very pleased with the size of the yolk sac, very encouraging!
They said we could have two growing normal and that one just implanted at a different day and thus was pulling nutrient/blood supply longer than the other. We just couldn't know at this point...so, glad to have one healthy guy at the least!
The options they prepared us for were - the smaller could be not growing and by the next US would be reabsorbing into the uterine lining; the little one could be growing fine and show on the US a day or so behind in size. I felt twins, Jen was not so sure!