High hcg levels??!!!

So, I had my results from my NT and bloodtest. It was done at 12w5d. Im now 18w2d. My dr told me I have a 1/20 000 for down syndrom, very low risk, wich is good. But, I have a 3 times higher HCG level than normal... he didnt seem concern but I read that it may cause many problems (molar pregnancy, risk of down syndrom..). Have you had some similar result? Did it end up with an healthy baby/pregnancy? Thanks!!!