This page has link to medical study that proves Tdap vaccine causes microcephaly and government knew it in 1991 but now they are falsely claming that it was caused by zika virus.

http://www.march-against-monsanto.com/1991-government-document-confirms-tdap-vaccine-causes-microcephaly/

Here is the link to that study if you don't want to visit the link above. This link is on government site as you can see from the .gov domain. This is one the most respected sites for medical science studies.
http://www.ncbi.nlm.nih.gov/books/NBK234367/