If you have had a scan, then the main reasons for a larger than expected uterus have already been ruled out. These are, first, that you are further on in your pregnancy than you thought, second, that there is more than one baby, and, third, that there is a fibroid present. The fourth is a very rare condition called a molar pregnancy. This is when a malformation develops at a very early stage of the pregnancy, so that instead of a baby growing inside the uterus, there is just a mass of cells. The treatment is to have this mass removed by D& C. This condition would have been seen on a scan, however. Another possible reason for your uterus feeling larger than expected is that you have more lax tummy muscles than you did during your first pregnancy. The position the baby is lying in can also affect how large the uterus seems. It’s also the case that the assessment of the size of the uterus is open to error! If you are having a 20-week scan, this should give you a better idea of what the situation is, but I don’t think that there is anything to worry about. I wish you all the best.