1.
The events that led up to a particular event happened one after the other until that event occurred.
Alan Tomlinson has reconstructed the events that led up to the deaths...
They had a series of arguments, leading up to a decision to separate.
PHRASAL VERB: V P P n, V P P n
see also lead-up
2.
The period of time leading up to an event is the period of time immediately before it happens.
...the weeks leading up to Christmas.
PHRASAL VERB: usu cont, V P P n
3.
If someone leads up to a particular subject, they gradually guide a conversation to a point where they can introduce it.
I’m leading up to something quite important.
PHRASAL VERB: V P P n