This squashes the heart and both lungs. While in the womb, the placenta provides the oxygen for the baby, who will grow normally. However, the lungs may not develop normally, depending on how squashed they are and how long the bowel is in the chest. In some babies, the bowel only goes into the chest at delivery and so the lungs are normal. Other babies have lungs which are so poorly developed that they cannot keep the baby alive after delivery and the baby dies very quickly.
Most affected babies are in between and have a degree of breathing difficulty.
These problems may be lethal. Most UK units stabilise the baby in Intensive Care on a ventilator, so that the lungs and heart can be assessed. The baby is often kept for several days until the optimal moment for surgical repair is reached. Most surgeons repair the hole in the diaphragm via the abdomen. If there is enough diaphragm, the two edges of the hole are stitched together.