Hey Mama,
My baby was also on the small side. He was only 2.1kg at birth. We regularly checked blood flow from placenta and heart monitoring. Doctor was going to induce early to be safe but my water bag broke at 36+weeks. When baby came out, his umbilical cord was knotted, explaining the weight. I would advise to check on baby as regularly as possible and follow the lead of your gynae.
Lena Tan