Please see here
http://www.immihelp.com/greencard
/adjustmentofstatus/medical-examination.html
Actually most of the Vaccinations we did in China, but we don't have the record. You can explain to them and tell Civil Surgeon that you are pregnant. For my case, he just did one which is safe for pregnancy. Then he provide me the complete vaccinations report.
For sure, You can do it later. Your baby is most important.