Tristan Thompson's Son Theo Poses With Mom Maralee Nichols on Her 1st Mother's Day

Nichols and her 5-month-old baby posed for a sweet, celebratory snapshot.

Maralee Nichols is celebrating her first Mother's Day with her adorable baby boy, Theo Thompson.

Nichols spent the day with her 5-month-old son -- whose father is Tristan Thompson -- and she shared a special moment as she and Theo posed for a heartwarming snapshot to commemorate the occasion.

The photo shows the proud mom in a flowing, off-white dress, embracing her infant son as they sit together on a white shag carpet.

Maralee Nichols

A rep for Nichols tells ET that the adoring mom and her son "are spending a quiet day together with loved ones" to celebrate the holiday.

The photo comes just a few months after Nichols revealed her son's name in a statement to ET in February.

"Theo, my little angel baby. I named you Theo because it means, 'Gift from God.' I had never been pregnant and had been told I might not be able to have children. I couldn’t believe I was pregnant, when I saw you on the ultrasound and heard your little heartbeat, I knew I would always protect you and keep you safe," Nichols shared with ET. "I love you more than you’ll ever know. You bring such joy and happiness into my life. My greatest blessing."

Nichols and Thompson were in a prolonged legal battle regarding the NBA star's paternity, until a paternity test proved him to be Theo's father back in January. Thompson is also the father to 5-year-old son Prince, whom he shares with Jordan Craig, and 4-year-old daughter True, whom he shares with Khloe Kardashian.

For more on the ongoing drama regarding Thompson's relationship with Nichols -- which occurred while Thompson was reconciling with Kardashian after previous cheating scandals -- check out the video below.