There is a little difference in strain on father body vs mother's body, plus there is this little procedure called birth. You know no biggie. Then many moms breast feed.
I suggest you open up biology book on difference between men and women.
UK moms gets 9 months, most of Western world also about the same. US moms should be treated the same. 6 weeks is a joke.
You realize what will happen when you do this, right? It will just mean that employers will be that much more hesitant to hire women in their childbearing years. Yeah, there are discriminatory laws - but it'll happen anyway. And you'll set back equal pay and equal opportunity in your attempt to do this. That's how reality works, and why you can't legislate reality away.