Hcg and miscarriage

Amber • 28 yrs old-married for 8 years. Lovebug born 11/3/09 BFP after miscarriage and before AF. Due end of August
If my hcg is doubling perfectly and I am having no bleeding or anything at 4w3days, how common do you think it would be to miscarry or something be wrong? I had one pregnancy prior and have a 4 year old son. My pregnancy had no complications. Insight??? Thanks