Hi Truck, Loss of sex drive after giving birth is really common, and there is no external answer out that will work, other than talking to your wife and finding if she knows why she doesn't want sex (does she just not have the urge anymore? Is she just too knackered and would rather spend her 'down time' sleeping? Is she so tuned into your little on that she just can't switch off her 'mummy' brain?)
There are loads and loads of reasons and causes of loss of sex drive (some of which might be hormonal and totally out of your wife's control).
I'd start with your wife and find out what she thinks the biggest issue might be. Once you know that then you can find out if having the house to yourselves for a night (or afternoon) might help, or if she'd like to go back to the start and start off with snogging and massages and shared baths with a strictly 'no sex' policy (sometimes taking it off the table for a month or two - when she knows that even if she wants sex you'll say no - can be enough to kick off interest and it removes the pressure she feels - because even if you're being a complete gent about it all, she'll know it's not 'usual' and she'll be pressuring herself and worrying about why she doesn't want it anymore)
No easy answer to the question though, really depends on you and your wife. I've had spells where I've totally lost my sex drive for months on end and I know it can put a real strain on things.
One thing I would say is that it has no reflection on you (or whether she still desires you) at all, she'd probably turn down Brad Pitt at this stage...
Sorry this probably hasn't been much use to you!