Pregnancy tests in Louisiana charter school

We have heard stories of pregnant high schools girls being discouraged--sometimes subtly, sometimes not--from continuing to attend their schools when their pregnancies are revealed. Some administrators believe these girls are a bad influence or that pregnancy is somehow contagious or--more nefariously and illegally!--that they should be punished. Alternative schools, GED programs, or just a recommendation to go away now and maybe come back later have all been proposed.
Still it was somewhat surprising to hear about a public charter school in Louisiana that not only kicks pregnant students out of its school, but mandates pregnancy tests for any girl they feel might be pregnant. (Refusal to take the test results in being banned from attending classes.)
The ACLU got wind of the test-and-expel policy and sent a letter informing the Delhi Charter School that their actions were discriminatory and illegal.
The school is planning to change its policy but apparently didn't even know that what it was doing was illegal. A Louisiana Board of Education spokesperson said he didn't know how rules around pregnancy applied to charter schools. Isn't that the board of ed's job?
This is what has been most troubling about this story. It seems that the schools that engage in pressure tactics (attend another school, penalties for pregnancy-related absences, encourage the GED route) probably know they cannot legally mandate the girl to leave. And while these actions are just as problematic (often because girls do not know their rights), the fact that people running a school--or a state education board--remain ignorant not just of federal law, but of the ways their beliefs about gender manifest in discriminatory policies and actions is discouraging.
Thank goodness for the anonymous community member who contacted the ACLU in the first place. No one at this chapter of the ACLU--despite the consistent number of calls it receives regarding the rights of pregnant girls--had never heard of mandatory pregnancy tests.