Are pregnant women allowed to provide care to an MRSA carrier?

No. Pregnant women are not allowed to care for infectious patients (e.g., MRSA patients) in Germany.

Background:
Laws such as the Maternity Protection Act (Mutterschutzgesetz, MuSchG) and regulations for the protection of mothers in the workplace stipulate that pregnant women should not work in hazardous areas. MRSA are dangerous for both the mother and the child. Pathogens pose an increased risk, especially in the case of direct, unprotected bodily contact with patients' body fluids or tissues.

Source:
Mutterschutzgesetz (MuSchG)

Ministerium für Arbeit, Integration und Soziales des Landes Nordrhein-Westfalen:
Mutterschutz in Alten- und Pflegeheimen, Stand 2015.