Bone marrow / stem cell transplant in children — what parents need to know

A bone marrow transplant unfolds over weeks and months, not days. Understanding each stage helps you plan practically and reduces the uncertainty that comes with not knowing what is next.

1. 1
   Stage 1 · Weeks before admission

   Pre-transplant evaluation and donor search

   Before any treatment begins, the transplant team conducts a thorough evaluation of your child's overall health — organ function, any active infections, and current disease status. If an allogeneic transplant is planned, a donor search begins. Siblings are tested first because a matched sibling offers the best compatibility. If no sibling match is found, the team searches national and international registries of unrelated donors, or evaluates cord blood options. Finding a well-matched unrelated donor can take several weeks. During this time, bridging chemotherapy may continue to keep the disease stable.

2. 2
   Stage 2 · Days -7 to -1 (before Day 0)

   Conditioning — preparing the body for the new stem cells

   Conditioning is the phase of high-dose chemotherapy (and sometimes radiation) that precedes the transplant. It serves two purposes: destroying any remaining cancer cells and suppressing the immune system so the new donor cells are not rejected. The child is admitted to a specially designed isolation room during conditioning. This is typically the most physically demanding part of the process — nausea, fatigue, mouth sores, and very low blood counts are expected. The team actively manages these effects and will explain each medicine they are using. Conditioning usually runs for five to ten days.

3. 3
   Stage 3 · Day 0

   Stem cell infusion — the transplant itself

   Day 0 is the day the stem cells are infused — a milestone that many families mark as a second birthday for their child. The infusion itself is straightforward: the stem cells are given through a central line (a tube already in place for the conditioning medicines), much like a blood transfusion. The process takes two to six hours. Your child will be awake and monitored closely. The stem cells find their way to the bone marrow on their own — no surgery is needed at this point. Day 0 is emotionally significant, but the recovery work begins in the days that follow.

4. 4
   Stage 4 · Day +1 to Day +30 (approx.)

   Engraftment — the new marrow begins to take hold

   After infusion, the transplanted stem cells travel to the bone marrow cavities and begin to establish themselves — a process called engraftment. Blood counts are monitored every day. Engraftment is confirmed when the neutrophil count (a type of white cell critical for fighting infection) rises and remains above a threshold for several days. This typically happens between 10 and 28 days after infusion, though it can vary. The period before engraftment is the time of highest infection risk — the child is in isolation, on preventive medicines, and receives close daily monitoring. Once engraftment is confirmed, discharge planning begins.

5. 5
   Stage 5 · Months 1–12 and beyond

   Recovery and immune reconstitution at home

   Discharge from hospital is a relief, but it is the beginning of a long outpatient recovery, not the end of treatment. For the first three months at home, clinic visits are very frequent — sometimes twice a week — to monitor blood counts, organ function, and signs of graft-versus-host disease (GVHD) or infection. The child must avoid crowded places, certain foods, and sick contacts until the transplanted immune system has rebuilt sufficiently. This typically takes six to twelve months and varies between children. Vaccinations given in infancy may need to be repeated, as the new immune system starts from scratch. Energy, school attendance, and normal activity return gradually — some children bounce back faster than expected; others need more time. We walk this journey with you at every step.