California SDI Tax

According to this page, the tax is 1% per year, up to $1008.80 per employee.

The 2013 SDI tax rate is 1.0 percent (.010) of SDI taxable wages per employee, per year. SDI is set by the California State Legislature and may change yearly. This includes the rate for PFL. The maximum tax is $1,008.80 per employee, per year ($100,880 x .010).

In other words, if you work approximately 6 years, and then have only 1 child, you are merely "earning" back the SDI tax you paid in when you take the 6 weeks of paid leave. (This is ignoring any other possible disability claim.) Hopefully, everyone is healthy and has no other need for paid family leave.

Assuming a flat income, and X years of work,  0.01XY of yearly income Y would be paid into the system. Then, when you have a claim, you would get the minimum of (6/52*0.55Y,1075*6) = minimum(0.06346153846154Y, 6450).

0.01XY = 0.06346153846154Y

0.01X = 0.06346153846154

X = 6.346 years

If you are paying the max every year (LUCKY YOU!)

1008.80X = 6450

X = 6.393 years

In conclusion, if you have a child more often than every 6.3 years, you come out ahead! (This ignores taxability aspect of the pay. This is an exercise in theoretical terms and is not meant to be used as advice in planning for child birth.)