Just wonder if extreme heat can cause you to go into labour early? Has anyone experienced this?

Why I ask is this -

One of the girls at work is 35w pregnant with her second baby & she went into labour yesterday. For those not in Sydney, the temp got up to about 40deg. So I wondered if the heat might've caused it to happen.

All is well with mum & bub & they managed to stop the labour, but they are expecting the baby to be born in the next few weeks.