Who's Baby Is It?

In 'The Waters Of Mars Trailer' there is a hidden clip of a women holding a baby. Since this clip was found, there has been lots of ideas to who the women in the clip is. The woman is most likely Rose and the baby is the meta crisis Doctor's. The women seems to have Blonde hair like Rose, but it could be the lighting that effects the hair colour.Why would Rose appear in 'The Waters Of Mars' and how?

I personally don't think it is Rose. I think it is Lucy Saxon's baby, because this would give the Master a way of returning. Some how the baby and the Master's ring from the end of series 3 work together to bring back the Master. We know Lucy Saxon and The Master are both returning, but how would the Master return from the dead? Could this be how he does it?