I don't think Claymores can become pregnant... under the vague impression that there's a whole lot going on in the stomach (lower abdomen) area that probably means (as someone mentioned above) that various things were removed. I'm going for the cell theory - because I guess when they fully transform, it means the Yoma cells might well have become the dominant dna or something scientific like that, rather than the human part?
We know that male ones weren't successful... and well, guys tend to have more testosterone, so could that be a contributing factor towards the acceleration to
We can also tell when a yoma is killed simply by the colour of the blood... haemoglobins cause the red colour for humans, so am wondering if there's any organism that is purple ... alas the only thing I can think of is aubergines or the common egg plant