How to stop the pressure to come back early?

[StuffedGrapeLeaves]

"Well new clerk only took five weeks!"  All the dingdangity time.

"I know! I feel so bad for her having to rush back to work so soon. It makes me really grateful I have enough leave accumulated to take three months. I don't know how she's doing it, but I'm certainly glad I won't have to."

I would do this.  It puts the boss on notice every time that you intend to take the full 12 weeks, without making it more aggressive.  If your boss starts being more aggressive, then other people have better suggestions on how to approach it. 

[Shoo]

"Well new clerk only took five weeks!"  All the dingdangity time.

"I know! I feel so bad for her having to rush back to work so soon. It makes me really grateful I have enough leave accumulated to take three months. I don't know how she's doing it, but I'm certainly glad I won't have to."

I would do this.  It puts the boss on notice every time that you intend to take the full 12 weeks, without making it more aggressive.  If your boss starts being more aggressive, then other people have better suggestions on how to approach it. 

I think this is the way to go, too.  It gets the point across without being too confrontational.

[MsOverThinker]

I'm kind of surprised that some suggest the "I feel so bad for her" line.  I would go with complete silence and just raise my eyebrows a bit.  It'll make supervisor think twice about what she just said/implied.  If she escalates at all, and says something like, "I don't know why you need 12 whole weeks", then I'd go the medical information route ("I'm sorry, but that's really between me and my doctor.") and then notify HR.

[Redneck Gravy]

Congrats on the new little one !

I had a C-section with #2 and was back at my desk at the end of week three (3/4 time)
whoo-hoo I don't feel special.  If I had been entitled to 12 weeks or 12 months I would have still been back at my desk in 3 weeks.  I was much younger, fitter and extremely driven at the time.  Today I might take 12 weeks if I had the darn flu.   

You are entitled to 12 weeks, take your 12 weeks - it's NONE of anyone's concern what other co-worker(s) did or did not do.  Continue to assert that you will be gone 12 weeks.

HR does need a heads-up, this sounds like a hostile enviornment is being created and they should be alerted.

[Cami]

I'm kind of surprised that some suggest the "I feel so bad for her" line.  I would go with complete silence and just raise my eyebrows a bit.  It'll make supervisor think twice about what she just said/implied.  If she escalates at all, and says something like, "I don't know why you need 12 whole weeks", then I'd go the medical information route ("I'm sorry, but that's really between me and my doctor.") and then notify HR.

I doubt a guy who's pressuring the OP into coming back a full 7 weeks early from a maternity leave to which she is legally entitled is going to be so sensitive as to note the raised eyebrow and silence AND realize that non-verbal communications are meant to shut him up. To people like that, silence = consent.

[WillyNilly]

You have gotten great advice so far, I can't add much to that. But I will say you might want to brush up your resume and start building your LinkedIn network, etc. Employers need to keep a comparable position open, not the same position. And this manager sounds like he's not going to be pleased with you gone for your full 12 weeks.  You might come back to a less desirable (to you) workplace. Better to have everything in place in advance in case you need to leave.

[checkitnice]

I'm not worried about getting let go.  There is another employee taking her second maternity leave right before me, and she is taking 12 weeks just as she did the first time.  It is standard to take 12 weeks in our office.  Everyone does it, no questions asked.  My (female, no children) boss hasn't been here too long and isn't totally familiar with the office culture yet.  I don't understand her need to have me back for our absolute slowest time though!

I'll take some of these suggestions into consideration before going to HR.