How Does The Baby Affect Grocery Spending?

I'd guessed that we'd spend more at the grocery store with a baby since he has to eat, wear diapers, etc. I've broken down exactly how much our spending has changed.

Anecdotal

Early on, there was the obvious spending on diapers and formula. However...I did all of the shopping with the baby by myself and it was all well-planned, so we made fewer impulse purchases. Since he's stopped taking bottles (he stopped at ~12 months) and fully switched to our diets + milk, we buy a lot more at the grocery store. 

At a minimum, I'd guess we've added 50% more fruits and vegetables, 100% more paper towels, and 10% more other foods to our monthly grocery purchases.

One anecdotal note on grocery shopping with a baby...it's significantly more fun. They're so curious. He also loves running down empty aisles. Often when we shop my wife will walk around with him while I get food, and if he sees me across the store he screams "Daddy!" and runs as fast as he can until he gets close to me. He then say says "Hi" and runs back to his mom. It's great fun.

Actual Data

Below is a plot of our monthly grocery expenses for the past three years.

There is a very clear upward trend that starts roughly a year after his birth. This corresponds to roughly when we started feeding him the same things we eat. It's a bit noisy and difficult to make out exactly how much it's changed, so I've included a plot broken up by year relative to his birth:

We very clearly spend more at grocery stores in his second year than we did in his first year or in the year before he was born (p < 0.01).

Two notes on this data:

• grocery spending includes things like toilet paper and diapers
• I did not factor out inflation