1) if there have been no health symptoms, building or acute, what is their reasoning for not waiting for your doc?
2) I HAD THIS PROBLEM. Although there are big head in my family, the kids' dad has a regular head and I have a small one, so the pediatrician kind of increasingly pressured me until my first daughter was like 8 months when he finally declared that she needed scanning and all this panic stuff. This was very very hard to hear. (Her head was literally off the charts. As was #2. #3 and #4 are 'just' big.)
Thank goodness I stuck to my guns. My first was a very happy, healthy (except right after vaccinations) baby.
I asked a key question: OK, what are the symptoms of hyper-whatever-it-is (the brain-swelling, was what he was hyping out on)? (Hyper cephalism, maybe.)
The symptoms were so incredibly the absolute OPPOSITE of my baby. As I recall, extreme fussiness (she didn't cry hardly at all), something about sleeping poorly (NOT a problem), and vomitting (in her first nine months she spit up, I kid you not, twice, and vomitted once). [yes, my other babies were more normal ;). ] And despite shooting down every single symptom that he could come up with except the big head (so, every functional _health_ _problem_)m he still tried to insist it could be a 'sneaky case' and I should go in to see the pediatric neurologist.
Whom he then called. Who of course said, having no input except that call, "well, um, yeah, probably they should come in." (Ask a surgeon how to fix a problem, they will say surgery.)
Frankly, the whole experience was our last regular commitment to allopathic care. When I ask for the science and all I get is "YOU MUST FEAAARRRRRR!"--forget that. At least when I argue from science and experience with my naturopath he listens.
So, yes, you might have a medical problem, and for sure listen and see if they can tell you any reasons why they are concerned that make sense to you as the most careful observer of your child. But remember that the medical schools teach doctors to consider all the problems that are possible. I mean, good grief, until recently they treated _birth_ like a medical emergency! And that's ignoring the very real problem doctors today face with liability lawsuits, and their very real need to try to protect themselves (and their partners, and their families) from lawsuits by people whose problems they didn't catch.
The last thing I will say here: those standard charts, at least last time I was looking into this, were all from the 1940s. Look around you in a mall or a church ... almost all the babies have "biggish" heads now, compared to pictures and cartoons of that period and earlier. We have better nutrition and are aiming to eat all of our omega threes and suchlike that specifically build brains ... and frankly, I think we are just seeing "success."
Watch your baby. Ask for help if the baby is sick. If the baby is fine, and all your friends and family haven't said "wow, he seems especially (some symptom that indicates the problem the medical professional is worried about)"--probably the medical professional is wrong.
If your intuition tells you to get the test, though, get the test. Because sometimes we know things we need to, for 'no reason.'
God bless!