Just a couple of points in response to what people are saying re: risks of getting it/benefits.
right now we are in a bit of a lull in terms of flu epidemics, but they come round inevitably - the next really nasty one is a case of when, not if. A moderately nasty one comes round every few years.
Your chances of catching it are higher when pregnant
If you do catch it, you will likely be much sicker than a non pregnant person. Your risk of death /serious complications is much higher.
Even normal, healthy people have a high complication rate from flu. I've had it four times in my life - three of those I've ended up with severe chest infections piggybacking on the initial viral infection and twice I've ended up with pneumonia. At the time I was in my twenties, fit enough to run a half marathon with no training, non smoker etc etc.
If you get flu, at best you'll feel utterly shit, which is not what you want when pregnant if with a new baby. At worst you'll end up with some nasty complications, including (sorry) being dead.
I know that every time this question comes up on mn I'm here banging on about it, but in my professional life I'm a scientist who works in drug development, I see the safety procedures these things go through and the years and years of post - marketing surveillance.
Honestly, please take it, it'd be awful getting flu when pregnant or with a new bub.