This diagnosis is often made early in pregnancy and many die before the pregnancy comes to term.
However, some do survive to delivery (almost half on some studies).
More than half again did not survive to their first birthdays and as there is no cure the focus should be on quality of life not quantity utilizing supportive /Palliative care.
Many of these children have a cardiac defect which leads to their death.
There has been a change in the pediatric approach to Trisomy 18 wherein if the infants are relatively stable with a more minor heart condition there are centers who will now accept them for surgical intervention.
I personally believe ;after looking after many many of these children over the past 20 years ) that again the focus should be on getting your child home to be part of your family and enjoy their life. If they then ‘declare’ themselves as fighters and are otherwise doing well a surgical consult may be warranted.