My daughter's girls every time they see her say she's very small. She was…

My daughter's girls every time they see her say she's very small. She was born at 8th month of the second week with a growth of 52. At the second month she was 58 cm. We will go to the pediatrician only in late month. Grandma says she's worried that her height is not normal. My height is 160 and my husband is 180.