One of the topics that come up often on the boards is shoddy book-keeping of the doctor's office, posts like
"My child is two years old and I am sure we had done all first year vaccines, but now we got called back for XYZ shots"
"I got a letter from the State saying that my child is not up to date, but s/he is"
"my child got his/her 4th DTaP at 12 rather than at 15 months and now we have to go back for a 5th, because the 4th doesn't count" *
"my child got his/her MMR too early and now it doesn't count" *
All of these are real life examples (2 from Dr. Bob's old board, 1 from Babycenter) and they illustrate one thing very clearly:
You have to keep a record of the vaccines your child get!
Now in an ideal world, your pediatrician hands you a vaccination schedule on your first well visit, including all info on the first vaccines, so you can read up ahead of time. S/he'll discuss with you whether you have any questions before the first shots and each time your baby is vaccinated, the little sticker on the vaccine vial that has vaccine name and lot number goes into a booklet like this:
that you get to keep. I have encountered such "best practice" with our second child - our first had 3 cards, one for each country she got vaccinated in, until we combined them into one. It is surprising, however, how often parents do not automatically get vaccination records to take him with them.
However, you need such records, so if you move or change doctors, you have proof of which vaccinations your child has had. These "Yellow Cards" exist world wide (the upper picture is an Ugandan one filched off the web, my daughter has one from California, my son one from Germany), they have been around for a really really long time - I have one, my original one is white though and I recently found my mum's and grandma's (proper record keeping during WWI and WWII, although mainly for smallpox).
It is even more important to keep your records if you are on an "alternative" schedule (for any reason - the European schedule my daughter had been vaccinated on for her first 9 months was very much "alternative" to what was recommended/required in the US).
As soon as your child is born, you can make up a vaccination schedule for him/her - the CDC has a handy tool, or find your country's National schedule and do it by hand. If you want to diverge from what is recommended, highlight this on the schedule. Take the schedule in to your doctor's appointment to double check you have done it right. Ask for the yellow card and then keep track of all shots. Also make sure that all vaccines are actually available in the combination that you want to give them - there are still parents out there who want to give monovalent measles, mumps and rubella, but they are no longer made by Merck - there are also periodic shortages in vaccines (in recent years for example the monovalent hib).
It needs a little planning, but it is very valuable, and, ultimately, your responsibility.
* that is actually a topic for another post