When Baylor University professor Darryn Willoughby saw Katy Humphrey's 4 1/2-month-old daughter starting to fuss in the front row of his class, he didn't think twice about scooping up the little one and and cradling her during his 55-minute lecture.

Humphrey, who is a wife and full-time mother, brought Millie to class earlier this month after her baby sitter canceled unexpectedly.

"Dr. Willoughby said if I ever needed to bring her to class, he was OK with it, so it made me feel relieved to know I would be able to learn and take care of my daughter," she told TODAY.

The 33-year-old student, whom Willoughby said rarely misses class, was not going to let the minor setback affect her attendance.

She traveled an hour to Waco, Texas, from her home in Salado, north of Austin, to make Willoughby's exercise bio chemistry class.

Humphrey's choice to pursue a degree in exercise physiology was inspired by her time in the Marines. She wants to be a physical therapist.

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"I was in the Marines for 14 years as a Pashto linguist and signals analyst, and after a few friends were injured in Afghanistan, I felt called to work with wounded warriors," she said.

Professor Willoughby teaches while holding 4-month-old Millie. Katy Humphrey

During the class on March 2, Willoughby, who has taught college for a dozen years, could tell that Humphrey was trying to prevent an outburst and becoming distracted.

So he did what he could to improve her learning experience — as any teacher would, he said.

"I didn’t do it for myself," Willoughby told TODAY. "It’s just about me looking out for and taking care of my students."

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"It was an issue more so just her being able to feel more comfortable and relaxed in class," he said.

Millie at 4-months-old. Katy Humphrey

And she was — Humphrey was able to focus while Millie seemingly had a blast hanging with the professor.

"I carried her around for almost an hour and she was totally content," said Willoughby, who has two girls himself. "We never heard a peep out of her the entire class."

This wasn't the first time Humphrey was in one of Willoughby's classes. Over the summer, she took his kinesiology course while she was pregnant.

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"[Millie] would always kick when she would hear him talk, so our joke was that she either liked him a lot or not at all," she said.

"We’ve become not only professor and student, but friends," Willoughby told TODAY.com. Katy Humphrey

And there's no doubt that Willoughby loves Millie — he's held her a few times since she was born, Humphrey said.

So she couldn't help but laugh when he motioned to take her again during the March 2 lecture.

"We’ve become not only professor and student, but friends," Willoughby said. "We have a really nice bond."