Silver, 3rd stage is when the placenta is delivered and what happens is that the uterus clamps down on the big blood vessels between it and the placenta. Placenta comes away, uterus clamps and contracts, blood vessels closed off.
One of the ways women used to (and very rarely still do in the West) die in childbirth is when this process didn't work which caused PP haemorrhage.
They therefore came up with a drug called Syntometrin. This helps the uterus to clamp down on the blood vessels and releases the placenta more quickly than when left to nature. This is called a managed 3rd stage as opposed to a natural one.
Unfortunately, very, very rarely it can happen too quickly and lead to a retained placenta - where the placenta is captured by the uterus and needs an operation to retrieve it.
Also, they used to give the injection just as the baby was in the process of being delivered so if there was a problem of the baby being delayed or getting stuck then the placenta would already be coming away and very, very rarely babies were damaged or died because of this (but this is NO LONGER deemed correct practise).
Typically now the injection is given after the baby is born and can be left for a while before the cord is cut. You then just get less time to wait for the placenta to be delivered (usually within a few minutes of the injection as opposed to 30-60 minutes or more without it).
With a managed 3rd stage you are likely to bleed less at delivery, but it's thought that there's the same amount of blood there so you have lochia for longer.
Almost everyone goes for a managed 3rd stage and it makes a great deal of sense. The benefits are less bleeding - con is potential of retained placenta. I don't know what the statistics are, and therefore the risks, of PP haem V retained placenta.
I decided to go for a natural 3rd stage but it wasn't in the end the best decision because although I didn't fully haem, I did lose more blood than my body could deal with (athough this may have happened anyway). Of course, as okie has shown, having a managed 3rd stage doesn't always stop haem either... but it stops it most of the time.
If I had another baby I don't know what decision I'd make to be honest. I'd have to really seriously think about it. I guess that if I was in hospital I'd go for natural. If at home, managed.
On another note, can I ask what everyone's baby's sleep patterns are like? Comma is sleeping most of the time still and I'm getting a bit worried. Even when he's awake he is mostly just really chilled out, especially if he's being cuddled. I know I should be grateful but it just doesn't seem right... and I'm being paranoid.