I work at Google and usually taking parental leave or even simple paid time-off are not supposed to be penalized. Come performance review season, if you've been absent for 4 out of 6 months in that review cycle, you are usually prorated and evaluated for the 2 months you’ve been around as if that work has sustained for the whole cycle. How much of this we can prove (that it doesn't impact ratings or promotions)? Probably not a lot. You’ll find that no company is willing to share that data to save their bacon.