(NEW YORK) — Chrissy Teigen took to Twitter Wednesday night to wish her son Miles a “Happy Graduation” after he spent three months wearing a helmet for medical reasons. In December, the mom of two revealed on social media that Miles, who was 6 months old at the time, needed to wear a helmet to correct his “adorable slightly misshapen head” and was seeing a physiotherapist to help the process along. Now 9 months old, Miles, whose father is singer John Legend, has ditched the head gear that seemingly corrected the common condition known as plagiocephaly or flat head syndrome. “Happy helmet-free day, no more helmet!” Teigen can be heard saying in a video shared Wednesday.

such a trooper for 3 months of helmet. happy graduation, Miles!! pic.twitter.com/atOIplfHLg

— christine teigen (@chrissyteigen) March 14, 2019

Flat head syndrome is caused by a baby remaining in the same position for too long. It can often be corrected by having the baby wear a specialty fitted helmet for up to 23 hours a day for four to six months. The condition affects one in four babies, according to Edith Bracho-Sanchez, a board-certified pediatrician and Global Health Fellow at Stanford. “Incidents [of flat head syndrome] have gone up since we said ‘back to sleep,’ which we absolutely have to do,” Bracho-Sanchez told ABC News’ Good Morning America, referring to the recommendation that babies sleep on their backs to reduce the risk of sudden infant death syndrome. Bracho-Sanchez said that changing your baby’s position in the crib, but still keeping them on their back, is very effective in preventing and treating the plagiocephaly. The same goes for infants that spend time in a swing or rocker. “Anything you can do to have them look both ways because their little bones are still so malleable,” she explained. The American Academy of Pediatrics said parents should first try physical therapy to see if a head shape problem will correct without needing a helmet. After Teigen shared the initial photo of Miles in his helmet, moms and dads began sharing pics of their own little ones wearing their helmets. Teigen’s latest post sparked a new thread of babies in helmets with parents captioning that they “can’t wait for graduation.”Copyright © 2019, ABC Radio. All rights reserved.