Is the work of a midwife (female birth attendant) in mixed-gender public hospitals legitimate?

A woman working as a midwife is a required and communal obligation (fard kifa'i) due to its importance in the sustenance of worldly affairs, just like medicine and accounting. There is a pressing need for midwives, similar to the need for female doctors. There is no objection to her working in a hospital, even with mixing (of genders), if there is a necessity or a strong need for it, provided that temptation (fitna) is safeguarded against, she fears Allah, and strives to avoid the causes of temptation.