In a massive relief to the family, one of the boys born conjoined and later separated has left the hospital 13 months later.

The brother, Carter Mirabal, remains in recovery after the December 2014 procedure, but the other twin, Conner Mirabal, can leave Wolfson Children’s Hospital in Jacksonville and can now be with his family.

Carter has not recovered as quickly, but both boys are doing quite well, the mother said according to a Fox News report.

The boys were conjoined from the sternum to the lower abdomen at birth, and were quickly sent to Wolfson for multiple surgeries. They were finally fully separated May 7.

Conner Mirabel, who recovered more quickly, was sent to Brooks Rehabilitation in November to receive inpatient physical therapy before going back to Wolfson for some pediatric medical care and another surgery.

Although conjoined twins face difficulties in both separation and recovery, and it remains a dangerous procedure, things are better for them than they ever have been. Recent advances in technology could make the process even safer in the future. Just last month, a study presented at the Radiological Society of North America’s annual meeting found that a combination of detailed CT imaging and 3D printing technology could be used in surgical planning for separating conjoined twins.

Conjoined twins happen about one in every 200,000 births, and survival rates are currently low and separation is difficult because so many of them share vital organs and blood vessels.

Scientists think that a combination of volumetric CT, 3D modeling, and 3D printing could better help surgeons prepare to separate conjoined twins, although more development work is needed.