Murphy, the former editor-in-chief of Parents magazine and a regular contributor to ABC's "Good Morning America," has gone through each one personally — her daughter is an 18-year-old college freshman and her son is a 14-year-old high school freshman.

The stages, she explains, are relative to where children are in their development, but they also help define the evolution of a mother's role.

Stage 1 — Altered States

This is the shortest stage in terms of time — from the moment a woman finds out she's pregnant to the "fourth trimester," Pleshette's term for the three months after the baby comes home — but it's probably the biggest adjustment.

Murphy urges women to do this sort of soul-searching early on so there is time to think about how you get from Point A, maybe a busy social life that's organized by a Blackberry, to Point B, feeling like you've had a successful day because you showered before dinnertime.

"You won't know day from night, but you'll also feel the bliss of lying next to your little miracle," Murphy adds, and that's what will keep you going.

Stage 2 — Finding Your Footing, Finding Yourself

Most new mothers can find their footing from the time their children hit the 4-month mark until the kids can walk.

Families settle into a somewhat predictable routine, which, although it is a different life from what mothers had before, it's a life they can live with, Murphy says.

This also is the stage during which many women go back to work after their maternity leave. Murphy's advice: Get used to the feeling of being torn between work and family. It's something you're going to have to deal with at every stage.

Stage 3 — Letting Go

The toddler years are "fraught with guilt, anxiety and occasionally anguish," according to Murphy.

"Toddlers are challenging, loving, wonderful and passionate but also highly unpredictable. And they have so much energy! Just looking at them is tiring," she says.

If moms don't make some time for themselves during this stage — even if it's just being alone while they change out of work clothes into play clothes — the whole family will suffer, Murphy says.

At the same time, 1- and 2-year-olds need a little time and space of their own as they begin to play with the building blocks that will eventually lead to their independence.

Stage 4 — Trying To Do It All

The preschool and early elementary years can be even harder than the toddler years because parents' expectations of their children don't always match reality. Just because the kids were able to sit through a nice dinner once doesn't mean they'll be able to do it every night.

"They (preschoolers) are still really needy," Murphy warns.

So, while it's tempting at this stage for mothers to begin taking on new projects of their own — volunteering for charity or filling up their social calendar — they should resist doing too much, she says.

"You think you can be perfect at everything. A lot of moms are feeling 'there's something wrong with me' if they can't do everything. But those are unrealistic expectations," Murphy says.

Stage 5 — Reading the Compass to God Knows Where

Ages 6 to 10 are supposed to be the easy years between toddlers and teenagers, but because it seems like kids are growing up faster these days, mothers can't let this stage slide by, Murphy says.

They should, however, let their children experience success and failure facilitated by their own hands.

"Moms need help understanding how to let their kids fall on their faces occasionally and to realize that their kids might not be smartest or nicest in the class. Those are not the worst things. ... But mothers have a real tendency at this point to see their kids as an extension of themselves and they don't want to be seen that way."

Mothers also might find themselves less involved in their children's lives, and, says Murphy, that's completely normal as children's own friends become more important to them.

But instead of pouncing on kids when they do open up, Murphy urges mothers to proceed with caution: "Ask yourself, 'What are the battles worth going to the mat for?' "

Stage 6 — Living in the Gray Zone

Preteens might see everything in black and white, says Murphy, but their world is gray.

First, things change fast. "What was right yesterday isn't right today," says Murphy.

Second, mothers will find themselves shifting between roles of parent and pal.

"It takes an ego of steel to navigate the preteen years, because one day your kid is going to wake up uncomfortable in their own body. And when she stands with one foot in childhood, the other in early adulthood, and struggles to maintain her balance, the person she will grab onto with a desperate, clawing intensity is you," she writes.

Stage 7 — It Gets Easier, and Then They Leave

During the teenage years, mothers and their almost-grownup children relive every other stage as they struggle through dependence and independence in their developed bodies and minds, Murphy says, but it's not as bad as it sounds.