Measuring small…or so I am told

So my specialist told me my baby is measuring small at 27 weeks. She’s 2 pounds.

They are using their own data gathered from other patients and measuring my baby against their proprietary data…? Do you know if this is common practice? According to all sources on internet and books I’ve read 2 lbs is the norm…could use some help here - should I get a second opinion I haven’t been jiving with this practice for a while…this was my second visit.