One thing that sometimes comes up in class is fear of having a very large baby. Sometimes this fear can be traced to our own fear of inability - whether we'll have the capacity to birth the baby we've nurtured, and whether birthing will change us forever. Sometimes this fear can be traced to anxiety we have talking with caregivers.
Here's a great article that explores the research around big babies, and it puts the realities of large babies in perspective. It's hard to tell from an ultrasound whether or not your baby is large. Even when a baby is big, the risks often change slightly, and in terms of "per thousand women". Childbirth of big babies is still just childbirth, and most times is not a medical event.
But it's not enough for many women to just gaze at statistics. Big baby fear can sometimes be a way of expressing the magnitude of change a baby of any size will bring. Being pregnant and giving birth will affect how we see ourselves, and we may doubt that our bodies will be able to do the hard work of bringing a new life into the world. We may worry that we won't be or can't be enough. You're not alone addressing these questions; confronting them, and finding your way through them, is one part of the very special work, and special reward, in becoming a parent.