Hello everyone, has anyone experienced difficulty gaining weight durin…

Hello everyone, has anyone experienced difficulty gaining weight during pregnancy and had someone give birth at 50kg? I'm 7 months pregnant but have only gained 4 kg, and I eat normally four times a day. My doctor keeps saying that my belly is small and it's hard to walk. Is it dangerous to give birth with low weight? Could something be missing in my body or is it genetically related?