Ok.
I am very pro-breastfeeding - dd2 is 16mths and has never had formula or cows milk to drink, I intend to feed her for as long as she wants to continue.
DD1 was breastfed until 9mths when I reluctantly stopped - I was back at work and found expressing too difficult and my supply dwindled until it eventually ceased.
However - when dd2 was 4 days old, she was admitted to hospital, jaundiced and dehydrated. My milk didn't come in until day 5. I am assuming the two are connected, although nobody actually said as such. To give the hospital their due, I was not encouraged to give formula - they put dd on a drip to raise her fluid levels and a lovely midwife helped me to get the latch right etc.
As a 2nd time mum, I was more or less left to get on with things, maybe if I had given the odd bottle of formula until my milk came in, we wouldn't have endured a terribly distressing time in the hospital.