Not one bit. That a nickel will buy you a piping hot cup of JACK SQUAT. An MPH, PA-C, or MSN/NP might look better toward your med school application, but an MA in child development? Hell no. Child development degrees usually fall under the college of education programs (usually geared for non-teachers) or family ecology programs. A master's degree in child development is not a science-oriented degree; it's an education/social science degree that has little bearing on pediatrics, which is a medical primary care specialty.
I'm not trying to discourage you, but if your goal is to become a physician, and you're looking for a back up plan, here's my advice:
1) Apply to MD and DO schools; many osteo med programs have less rigid admissions standards, but will provide you with an excellent medical education. Check out Lake Erie College of Osteo Med, New England College of Osteo Med, Des Moines University, etc. If you go to the American Osteopathic Medical Association Website (not sure of the URL) and look under education, you will find a link to all the US DO schools. Check them out. Don't apply to MD schools only.
2) If you are rejected from MD and DO schools, consider going the Nurse Practitioner (NP) or Physician Assistant (PA) route. This will entail about 2 years of graduate work + licensure and clinicals. If you go that route and practice a year or so, you could get into a DO program without a problem. Or...just practice as an NP or PA and work in peds.
3) You might also consider pharmacy school (PharmD), dental school (pediatric dentistry), or optometry school. You can still work with kids and be a "doctor". Also, you could get a PhD or PsyD in clinical child psychology and work with a pediatric/adolescent population as a psychologist.
Lots of options. Look into them.