I had my little girl with midwives in Oaxaca and know of numerous. The directory page in the Parto Libre Mexico site (here's the linkbelow) will give you a Oaxaca section and you'll find the details of the midwives by clicking on their names. Cristina Gelante and Araceli Gil attended my daughter's birth and were wonderful. Lauren Beam, also a midwife, is also a great contact for prenatal and postnatal yoga. http://www.partolibremexico.org/directorio.php#
Good luck with it!