If you think that it is, you aren't alone:
A new Pew Research Center analysis confirms what many moms already know: the work of parenting is way more exhausting than work work. Analyzing data from the Bureau of Labor Statistics’ 2010 "Well-Being Module" of the American Time Use Survey, Pew found that parents rate 12 percent of childcare tasks "very tiring," but only 5 percent of paid work-related responsibilities as such. Childcare is even more taxing than housework, with 7 percent of household chores classified as the most tiresome.
For me, I think it's harder because it's not as controllable as your work environment. Children can be very unpredictable!
What do you think?