Low Beta Hcg levels

Today I got a phone call stating my level were extremely low at 418. According to quest Diagnostics it should be between 500-1000 and according Labcorp its should be between 10-750. Does it matter which lab I reference? I am 4 weeks and I’m so afraid I’m losing baby. I also been cramping since I found out I was pregnant last week. I’ve never experienced that with my previous pregnancy. What are your thoughts?