Under the policy, which appears in a Lakeview high school gym syllabus, female students who miss swimming because of their periods must have a parent submit a written note or email identifying the length of their menstrual cycle before they can make up the missed days.

The syllabus states: “Female students will be given the opportunity to make up days, which are missed only because of their menstrual cycle. A written/email note from a parent stating the length of the menstrual duration is required, so the student can make up the days.”

“Students will complete dry land workouts to be able to make up the days,” it continues. “Students will not just sit out. Each day that is not made up will be considered a non-participation day and place the student on the grade reduction scale.”

The requirement caught the attention of Andy Amsdill, whose daughter attends Lakeview high school. Amsdill told WXYZ Detroit that he was stunned when he saw the requirements in her gym syllabus.

“The teacher wants us to either send a note or an email with the suspected length of the cycle which, by itself, is ridiculous,” Amsdill told the outlet.

Menstrual cycle length can sometimes be difficult to predict, and the US National Institutes of Health estimates between 14% to 25% of women experience menstrual irregularities. Irregular periods are even more common in young girls.

Amsdill later told CBS News that other parents contacted him after he spoke publicly about the syllabus, saying they were glad he had brought attention to the issue.

Among them was Bryan Shishakly, whose daughter is now a sophomore at Lakeview. Shishakly said she faced the same requirement during her freshman gym class last year and that it affected her grade.

“My response was like, ‘If they ask, you have no obligation to tell them,’ and it did affect her grade,” Shishakly told CBS. “She’s a straight-A student, and she ended up with a C in gym, and I don’t know how fair that is since it’s only going to apply to the girls at the school.”

The Lakeview public schools superintendent, Karl D Paulson, issued a statement that read: “We recently became aware of a parent’s concern relative to certain class expectations. Given our commitment to partnering with parents to address any issue that might arise, we immediately sought to schedule a meeting with the parent to engage in a conversation about the concern.”

It added: “We look forward to meeting with the parent in the coming days and working collaboratively with that objective. The Lakeview school district remains fully committed to educational excellence and best practices in all it does.”