Table 1

Proportions of infants, who have survived a given number of days, by total length of survival. For example, if counselling the parents of an infant with trisomy 13 who has survived for 14 days then there is a 60% (35 to 85% CI) chance that the infant will survive to the age of 1 month and a 7% (0 to 19% CI) chance that they will survive for 1 year. The revised median survival times with confidence intervals that do not overlap with those calculated at birth are marked with an asterisk

Observed length of survival (95% confidence limits)
Time already survived1 day1 week1 month1 year
Trisomy 13
Birth75% (60 to 90)50% (33 to 67)28% (13 to 44)3% (0 to 9)
1 day67% (48 to 86)38% (18 to 57)4% (0 to 12)
2 days76% (58 to 94)43% (22 to 64)5% (0 to 14)
7 days56% (32 to 81)6% (0 to 18)
14 days60% (35 to 85)7% (0 to 19)
30 days11% (0 to 32)
Trisomy 18
Birth88% (81 to 95)43% (32 to 53)25% (16 to 34)2% (0 to 6)
1 day49% (37 to 60)28% (18 to 39)3% (0 to 6)
2 days58% (46 to 70)34% (22 to 46)3% (0 to 8)
7 days58% (42 to 74)*6% (0 to 13)
14 days88% (74 to 100)*8% (0 to 19)
30 days10% (0 to 22)