Forgive me, but I think I'm suffering from postpartum depression. How could Garry Trudeau have left us, how could he have just dropped Joanie and Rick's baby into the world and taken a powder? I think we ought to sue the man for desertion.

I'm sure there are a host of other reasons why I'll miss "Doonesbury." But frankly, I would have loved to see how our cultural observer presented these parents in the world of mid-life babydom.

The way I figure it, subtracting a few years for literary license, Joanie is pushing 40. She has already been run through some capsulized version of our social history.

She was a mad housewife (as in Diary of), a consciousness-raised wife, a runaway mother, a divorcee, day-care worker, a law student. She got a job in Congress and had what trendy magazines call a "spouse equivalent" who became a spouse. Then she did what her peer group seems to be doing: she got pregnant.

Needless to say, I expected it. In the past year, I have read any number of treatises extolling the virtues of post-30, post-35 pregnancies and motherhood. Most of these women, unlike Joanie, are pregnant for the first time, and pregnant by planning--serious planning.

The women who get into the media in their maternity clothes or maternal pose seem to be television reporters and actresses, lawyers and executives. Having moved up the career ladder, what they want next is a baby. What they have next is, we are told, bliss.

I find the wave of mid-life babies fine, dandy and appropriate. I am enough a creature of the times to suspect that we are more able to deal with children in our lives when we've come to grips with the issues of our own childhood: Who am I? What can I do? I think maturity is good for maternity.

But as a veteran mother who once hired a babysitter so that I could take a bath, I find the reports I have read out of Older Motherdom just a touch too glowing. It's motherhood without the diapers, if you receive my meaning.

From what I observe, mid-life parents are not really allowed to complain. It's become socially unacceptable for a 37-year-old financial analyst to moan about the impossibility of getting her baby into a snowsuit. It's become socially unacceptable for a two-career couple in their forties to long out loud for a weekend alone.

Much of the silence is self-imposed. Older people with successful jobs and successful marriages have greater expectations of themselves as successful parents. It's the perfect-parent syndrome. The two-career couple with a history of competence may have trouble confessing to a child with colic. A manager with 10 years of business experience may have trouble admitting that she's overwhelmed by the simple problem of getting a baby and two bags of groceries in the house together.

But some of it is also imposed by the world.

When I was pregnant in my late twenties, during the late '60s, chaos was an accepted condition of life as a new mother. So was mutual support--the adult play group. In the early 1970s--right about the time Joanie left home--mothers who were continually ecstatic were considered candidates for consciousness-raising classes.

Now we are dealing with a larger number of couples who have had careers and choices. They have consciously waited, they have carefully chosen--from amniocentesis to LaMaze. It seems that because they want these children, they are expected to give unending imitations of joy. They made their crib; they can lie in it.

On the whole, the new parent at 40 probably has a great deal more in common with the new parent at 25 than we normally credit. Even successful people who deal with large problems efficiently have to learn new skills to deal with little people. Goals, five- year plans, five-hour plans--all pale in the face of a six-month-old with his own agenda.

Parents of newborns, willy-nilly, live in The Now, and The Now is a 3 a.m. feeding. Whether they are 40 or 25, they experience the same stress, and need the same support.

I wonder how Joanie and Rick would have borne all this. How would Rick, that vague soul, have tackled fatherhood? How would Joanie have done it this time? We could use some mid-life reality.

By the time Trudeau comes back, his creative offspring will be 20 months old, and sleeping through the night. So will Rick and Joanie. But until then, maybe even a comic-strip father deserves some paternity leave.