Earlier this summer I had an epiphany. It wasn’t exactly the happy kind. It was more the hysterical, don’t-know-if-I-should-laugh-or-cry kind.

I was sitting with my baby on my lap, watching my other children play, and I was thinking about how much work this baby was, and looking forward to when she would be a bit older. You know, because then, I thought, my life would finally get back to normal again.

That is when it hit me like a dodgeball to the head.

My life was never going to be “that” normal again. It would never return to the “normal” that was my life as a mom of three children.

Because I now had four. I would now always be a mother of four.

I swear my heart started palpitating and my eyes watered. I had to take some deep breaths. I had been living a lie for the last nine months of my life — I kept telling myself that I just had to get through this next year and a half or so — but, no. I would still have four children in a year and a half. Sure, their ages and stages would be different, but our family was permanently altered.

I remember being told by other moms who work outside the home that the fourth child did them in. They could no longer manage the competing tasks of Work and Mom, and they quit their jobs and devoted their full time to mothering. I also know a working mom of six, a doctor, who once said that, in her observation, Mormon women have one more child than they can handle.

I worried about this a lot while I was carrying my fourth child; I kept thinking, “is this my one too many?” I kept thinking about something a mom of eight once said to me, when I asked her how she did it. She said, “One child took all my time. Two children took all my time. Eight children took all my time. It didn’t matter how many I had, they would take all my time.”

I can see how this is true. However, I can also see how my lifework becomes much denser as each child comes to our family.

Now, as our fourth celebrates her first birthday this month, has accepted (after lodging several complaints) that she must wear shoes outside since she is walking, and is starting to string intelligible syllables together, I ponder how our family life has changed with her in it.

I have noticed that some things about mothering become easier with subsequent children. You learn processes and strategies for all the main stages of childhood as you go, so you are not always reinventing the wheel. Also, if you are lucky enough, at least some of your children will play well with each other, and occupy themselves long enough to let you do the dishes and make the dinner.

However, I have also noticed an interesting phenomenon I hadn’t guessed at before I had multiple children. I call it The Law of Exponential Parental Work.

When you have one child, you have one child’s needs to meet.

When you have two children, your work doesn’t double; it nearly triples. You have two children’s needs to meet, true, but you also have the relationship between the two children to nurture, manage and police. This involves all the lessons about sharing, and not hitting, and brokering deals between crying siblings who both want to “help” make the dinner mommy is working on (when of course you don’t really want any “help,” but you can’t actually say that.)

When you have three children, you not only have three children’s needs, but also the relationships between #1 and #2, #2 and #3, and #1 and #3. In other words, about six times the work as one child.

Do you realize how much work four children must be according to my law?

If I were to express this phenomenon mathematically, I think it would look something like this (where “R” stands for relationship):

Child A + Child B + Child C + Child D + R(A+B) + R(A+C) + R(A+D) + R(B+C) + R(B+D) + R(C+D) – (times they all get along) = All My Time.

Four children and all their relationships total 10 entities that require my parental attention.

I think I have figured out why so many moms I know quit their jobs with the fourth. It is not because childcare is too expensive. No.

The fourth child does you in because it is nearly impossible to have four and not have them spread far enough that they are experiencing completely different stages of life — at least one is likely to be in school, and that comes with a huge host of new issues to cope with.

One mom of four I know has one in high school, one in fourth grade, one in kindergarten, and one in diapers. Their individual needs are so disparate that her job description, as a mom, is twice as long as a mom whose children are all below the age of, say, five years old.

My one solace is that I hear it supposedly doesn’t get any worse if I have any more children. The moms I know with more than four say everything after four is the same — you lose your sanity with number four, so there is nothing left to lose with number five or more.

But don’t tell my husband. I am pretty sure the assurance that I will never again by sane anyway is not the best argument for adding to our family.