Sometimes, when I'm taking care of my daughter, I get the same fraudulent feeling I did in graduate school: any day now, I think, somebody is going to realize that I am not qualified to do this and will have me replaced. It didn't happen then, and it obviously won't now, but the feeling underscores the common thread between both experiences: guilt.

Oh, the guilt. In graduate school, I felt guilty pretty much every minute that I wasn't working on my dissertation. Now, I feel guilty when I'm working, because I'm not playing with Nora. When I am playing with her, I feel guilty because I'm not working and am therefore flirting ever more dangerously with missing a deadline. Only when she's napping can I work with impunity, fired by the happy thought that I have meritoriously gotten her to get the rest she needs—but if I stop to email a friend or check out a new website, then the old, familiar guilt of not working rises up to the surface.

Surely, though, I don't have to explain these feelings to any other mother. Constant, gnawing guilt at not doing it all every single second has got to be the defining feature of post-feminist motherhood. To me, feminism means that all people, men and women, have the equal right to choose what they want to do, but every choice afforded us by feminism by definition means not only choosing to do something, but also rejecting its opposite—and after just a few months it's already clear that in the murky, day-to-day throes of motherhood it's all too easy to regret or at least wonder about every single road and faint trace of a path not taken.

I have the good fortune to be able to work at home as a freelance writer, mainly on my own schedule, and the further good fortune to have an easy baby who lets me do so, by and large. (Of course, one of the things I have learned in four short months of motherhood is that even an easy baby is not actually easy all the time.) I feel—surprise—guilty even telling you about my further good fortune, which is to have a husband whose work schedule means he can take care of Nora in the mornings most days.

To feel guilty for having too good a baby and too easy a setup must be the new mother's version of white liberal guilt. I was thrilled when Nora started to sleep through the night, but hesitant to tell people for fear it would seem that I wasn't having the quintessential new-mother experience, and also for fear that my new-mother friends would somehow feel bad about their own experiences, if their babies weren't doing so. Plus, I had an extra little nagging feeling that maybe I should be getting up with her, feeding her more, keeping her growing on schedule. That feeling was compounded when we went to the pediatrician for Nora's four-month appointment and found that her weight gain had slowed considerably.

The pediatrician wasn't worried; she pointed out that Nora is clearly perfectly healthy, rosy-cheeked and chubby and growing at her own pace, which happens not to be as fast as some other babies. My husband wasn't worried, either. But I was, and what's more, I instantly felt like it was all my fault. After all, every drop of her nourishment comes directly (or indirectly, in the case of bottles of pumped milk) from me. Shouldn't she be gaining an ounce a day, like my breastfeeding book says? Was I not feeding her enough? Was my occasional secret impatience to have her finish up so I could catch up on my email somehow leading her to eat less than she should? Never mind that I feed her on demand and that she seems perfectly happy with the amount she eats; never mind that I completely trust our pediatrician; never mind that common sense and a cadre of supportive friends assured me that she was right and that Nora is the picture of health. Somehow, in some way, guilt was determined to crop up.

For me, the very delights of motherhood, paradoxically, drive and engender the guilt. The look of enchanted surprise Nora shoots me whenever she catches a glimpse of me is wonderfully gratifying; nobody has ever looked at me with such wondering joy, as if I were the sum of all that made life worth living, unless perhaps my own mother did when I was an infant. I usually get that look when I get in the door from a brief run that I've spent hoping she hasn't needed feeding, or else when I come downstairs after working for a couple of hours. Even as I smile back with pure pleasure in her adoration, in the back of my head I'm wondering if I was away too long.

Lest you come to the conclusion that I am merely a neurotic head case, I should say that I have managed to avoid letting these feelings paralyze me. I often work with Nora playing in her Fisher-Price Ocean Wonders Aquarium Gym in my office; even as I type this, in fact, she is grabbing for a jingly fishie and flailing about to its infantine calypso beat. She seems perfectly happy, and I would feel even worse if I weren't working.

Writing is an essential part of my life, and work for me comes under the heading of affixing my own oxygen mask before assisting others. I have to stay sane, and stay myself, in order to take good care of Nora. Besides, baby may not need a new pair of shoes—she is amply supplied with adorable Robeez—but Mama needs a new pair of knee-high brown boots, preferably with a moderately high heel and toes that aren't too pointy. (Suggestions for where to find the perfect boots gratefully accepted, especially if the places are online shopping sites with a liberal return policy.)

It's not that I want to give up working or motherhood, and on the good days I don't feel like a fraud at either pursuit. It's just that combining the two is already such a delicate balancing act, and I can only imagine that these issues get harder and harder over time—especially as kids learn to exploit their mothers' sensitive internal guiltometer on purpose rather than accidentally. As a friend of mine with a toddler said to me the other day in the context of a discussion of bedtime rituals, "If you're ever going to let them cry themselves to sleep, do it before they can say 'Mama.'"

Nora is a long way from saying "Mama," and we have been letting her put herself to sleep, with a fair bit of success—but not without a cost in parental agonizing over whether it's really all right. Deep down, though, the guilt is mitigated by a knowledge that it's all to her own good to be able to fall asleep unassisted. And I also feel sure that it will be good for her that I'm pursuing my work, my interests, and even the perfect pair of boots. No doubt I have plenty of failings as a mother already, and will develop even more over the decades to come (I suspect that those shortcomings will peak in about fourteen years, in Nora's eyes at least), but at the center of all my efforts with her is myself, the core of who I am. Far from being a fraud, I'm the only person who is qualified to be Nora's mother. If I let that core go or push it away in a misguided effort to be selfless, I will crumble, leaving me unable to do my inadequate best to guide her into childhood and adulthood. And that really would be something to feel guilty about.