Not let down, no.
The other thread (and ones before) has shown what a hugely emotive subject it is, and the many issues it seems to embrace as people discuss the 'rightness or wrongness'.
Research has shown that there are multiple factors as to why women undergo abortions between 20 & 24 weeks;
The majority have had delayed discovery (or acknowledgment) of the pregnancy for many reasons (irregular periods, breastfeeding, menopausal, denial)
The second delay comes as women are given time and support to consider their decision.
Further delays are then often experienced in the system.
Hence, a pregnancy at around 16 weeks may easily become an abortion at 20+ weeks.
For others, there are a change in circumstances (health of foetus included but perhaps marriage breakdown, violence or similar).
It is possible, for severe abnormalities, to abort up to term, but health professionals tend to push through before 24wks since the law is very fuzzy after that.