Sorry but nothing....
I was actually at work the day before (37 weeks). Went home, had a good sleep then woke at 6.30am needing the loo.
Got up and waters broke (thankfully I’d got to the bathroom).
Contractions started almost immediately.
Woke DH, got childcare sorted for DSD, called work to say I wouldn’t be in, then walked waddled the 10 mins to the maternity hospital and got there by about 9am (we loved them very near to the hospital and due to one way systems it would have taken far longer to drive - DH offered but I was the one who wanted to walk
).
DS was born at 12.30pm.
Went to the toilet, BF’d DS, had toast, put make up on for lovely newborn pictures. Met parents just as we were preparing to walk home I desperately wanted to have a bath in my own home with my fluffy towels and not the deeply unpleasant hospital bathroom littered with used sanipro, blood on the floor and pubes in the bath.
Got home by 2.30 and had lovely cuddles/feeds with newborn surrounded by family who kept giving me tea/food the moon if I’d asked for it.
Went into work the next day with DS to pick up stuff I needed (as I’d expected to be there so not packed up).
All in all I’m grateful I had apart from the squalor and filth in the maternity facilities - though to be fair the birthing room was very clean a very good experience.
So upshot is you might have no warnings at all 