Having children is a wonderful thing, but it can also throw your finances for a loop. I often like to joke that my kids are like little money vacuums, because they manage to suck every last dollar out of my bank account. Of course, the cost of raising children will vary depending on where you live and what sort of lifestyle you choose to lead. But these are the realities I've faced since having kids, and I'm sharing them so that all of you future parents out there know what to expect.

1. The little things quickly add up

Most weeks, my son, who attends public school, brings home fundraising or event forms, and much of the time, I participate, whether it's $5 here or $10 there. My daughters, who attend extended-day preschool so that I can work, often do the same. Similarly, there are times where I'm forced to take my kids food shopping with me, and inevitably, I always end up letting each pick one item that wasn't on my list. The logic is that an extra $3 times three won't necessarily bust my budget.

Woman reading to a young girl and boy.

IMAGE SOURCE: GETTY IMAGES.

You know what, though? All of these little things can really add up, whether it's school-related obligations, allowance money, occasional treats, new socks when the old ones rip, or whatever seemingly minor item comes up out of the blue. As such, I've learned to actually put a "miscellaneous" line item in my budget so that I'm better planning for these cumulative expenses.

2. Your kids will cost you more as they age

Many parents are overwhelmed by the idea of having to buy diapers in bulk and spend money on baby food. But child care costs aside, the infant period of your kids' lives might very well be your cheapest. As your kids grow up, they're likely to develop hobbies, want toys, and ask to do activities like dance or martial arts. And if you think these classes don't cost something in the ballpark of $100 or more per month, do some research and prepare to be shocked. I know I was.

3. You'll spend a fortune on child care

Unless you're fortunate enough to have a retired grandparent to watch your kids for free, you'll need some form of paid child care until your little ones are eligible to attend school. And those costs are downright astronomical. The average weekly rate for an infant in a day care center is $211, according to Care.com, while the average weekly rate for a nanny is $580.

Even once your children are in school, if you work full time, you'll need to pay for before- and after-care programs that can cost several hundred dollars a month. And let's not forget that school lets out for the summer, so if you have a job and aren't a teacher, you'll need to pay for camp.

The good news is that if your company offers a flexible spending account for child and dependent care, you can allocate up to $5,000 in pre-tax dollars to pay for that expense. The bad news, however, is that if you have multiple children or require full-time child care, that $5,000 is probably just a drop in the bucket.

4. You'll have months where you struggle to save a dime

My husband and I are solid savers, but some months, we just don't manage to come out ahead. And it's not just those times when we go on vacation or pump money into home improvement projects; often, it's a matter of child-related expenses impeding our goals.

Recently, I had a month where I spent close to $1,000 on medical care for my kids. Much of that included a dental procedure for my son that our insurance plan wouldn't cover. Either way, that $1,000 threw us for a loop.

Another time, our camp payments came due at the same moment we had to pre-pay part of our preschool bill for the year (doing so snags us a major discount). That was a doozy.

The point is that kids have a way of thwarting your savings efforts. If it happens once in a while, we roll with it, but if you find that you're unable to save on a regular basis, you'll need to reexamine your budget and cut back on non-child-related expenses.

None of this is meant to discourage anyone from having children. Rather, if you're going to have kids, be prepared so you're not caught off-guard after the fact. Remember, the joy your children bring you is something that can't be measured in dollars. And that's one thing that definitely helps soften the financial blow.