First, I really think that this fails to credit the very skilled and very real effort that was put into him by his medical care providers. That still is. It fails to credit what has been learned across millions of other babies. It fails to acknowledge that he did need support and that support was provided. And that's something I think we can all get behind.
Second, if he's a miracle, why him and not a different baby who hasn't had his good outcome? Using the term miracle somehow leaves me feeling that there is an implication that he earned it somehow and anyone who has spent time in a NICU can tell you that that is not the case. Being a good person or wanting it desperately is neither sufficient to ensure a good outcome. If a family could ensure a good outcome just by wanting it enough, there are some stories I know among just our friends that would have ended differently.
Third, I think it makes it sound passive on Chiron's part. And yes, we normally think of gestating as passive, but I saw Chiron during that time he was completing his gestation in the NICU and he definitely gave of himself to fight and continue on. He is definitely a part of his success story.
2. A highly improbable or extraordinary event, development, or accomplishment.
Looking at these definitions, I've found one more objection. His continued existence, and even looking like a pretty great outcome, is neither surprising nor improbable. The likely, or ordinary, outcome at the time of his birth is that he would survive and with a positive outcome.
Are we very blessed? Yes. We were blessed that we had great medical care that allowed us first to keep him in for six weeks and then to care for him excellently after he was born. We are blessed in our friends and family in our support system. We are blessed that a negative extraordinary event didn't occur. But do I think he is a miracle? No.