A grim mortal calculus met first-trimester nausea. My husband and I learned I was pregnant just before he drove my stepson to college. As you might guess, the pregnancy was unplanned. My husband was 56 — that would make him almost 80 by the time this kid was out of college. I was 42, so I’d be in my 60s with a teen and an elderly spouse. And what if I, like both my parents, got cancer in middle age? Who would be there to finish child-rearing?

I believe in abortion. That wasn’t my hesitation. In 1992, I joined several hundred thousand protesters on the National Mall to march and rally in support of abortion rights. Six years later, I drove a friend to a clinic to terminate her pregnancy.

Yet I’d never known of anyone in my situation considering an abortion. I didn’t fit the profile you tend to hear about: an impoverished teen, overwhelmed by the responsibility of raising a child and faced with the prospect of having to drop out of school. I wasn’t like the friends of mine who had abortions in their 20s when we were single and broke. I was happily married. Both my husband and I had established (if not especially lucrative) careers. And we were veteran parents. In addition to my stepson, we had a six-year-old son. We could do this — if we wanted to.

Did we want to?

For my husband, the answer was a pretty definite no. When our son was a baby, we’d talked about having another child, but my husband, a caring, present father, flexible in many ways, was done. He (only half jokingly) talked about wanting to enjoy “a window between child-rearing and death.” Not much had changed since then, except that we were older, and the timing was worse. My husband also was ready to leave the nonprofit leadership position he’d had for 18 years. I’d told him, “Quit your job, and we’ll figure it out.” With another child on the way, though, it would be harder for him to take that risk.

When I raised the possibility of abortion, my husband was surprised and uncharacteristically silent. He didn’t want to say anything that might pressure me to abort. He also wouldn’t say, “I love you, and I want this baby.”

As for my own feelings, I was uncertain. I come from a family of four kids, and I adore my three younger siblings. I was excited by the chance of having a daughter. And the fact of the pregnancy trumped my husband’s former objections to another child. In the bluntest terms, I had won.

Yet this new baby, should the pregnancy go to term (not a given considering my age), was not the peer-sibling I’d advocated for five years earlier, nor was I the same baby-centered mommy. I’d been glad to move beyond strollers on the subway, diapers, naps and the need to be home by 7 p.m. With our son in first grade, I was mentally surfacing from a long and lovely dive. I’d continued working when he was born — as a playwright and teacher — but often the best I could do was manage the modest projects before me. I couldn’t dream. I couldn’t plan. Now I had started thinking forward again, my brain active all the time. I wasn’t sure I wanted to dive back down.

I thought about the women I knew who had their first children in their 40s or surprise youngest kids. I wondered why everyone seemed to welcome serendipity, while most mornings I woke up hoping I’d had a miscarriage. Whatever I decided, it would mean a loss — in my work, in my marriage, in our family. I was old enough to know you can’t do everything.

I went to the wonderful ob-gyn who had delivered my son and told the nurse midwife that this was an unintended pregnancy, that I would probably terminate. She instructed the ultrasound technician (who always seemed to be in some state of pregnant herself) to turn the monitor away. But the technician left the sound on by mistake, and I heard that pack of horses heartbeat before she jumped to shut it off.

I wish I hadn’t heard that sound. But even that didn’t shout down the inner voice I heard as I cooed over friends’ babies or watched hale young parents hoist kids to their bodies: “I do not want this.”

I had the abortion.

At the clinic, I was struck that both the woman before me and the woman after me already had kids at home, and spousal-looking men in the waiting room. It turns out that 60 percent of women who have abortions are already mothers. As I’ve become more of an abortion-rights activist, I’ve learned that married mothers represent a subset of secrecy and shame within some very progressive circles. I wasn’t as anomalous as I’d thought.

And while married mothers in their 40s contemplating abortion don’t face the same trade-offs as unmarried teens, the trade-offs are real. After the abortion, I started pushing harder in my work. My therapist asked, “Are there any things that have happened since the abortion that would not otherwise have been possible?” The list surprised me: three commissioned works for major theaters (two requiring extensive research travel), a new academic job and a fellowship that enabled me to complete a play I had procrastinated on for years.

That hasn’t made the loss any less painful. A year ago I wrote an essay for The Washington Post about wanting to be more actively for abortion rights — but didn’t mention my own abortion. Part of my reticence stemmed from wanting to protect my young son (now 8) and avoid squeamishness with my stepson (now 21). But I also was grieving. And the idea that people would judge me as a bad mother, both for accidentally getting pregnant and for ending the pregnancy, made me feel worse. I didn’t want to expose myself and my family in order to make a point.

Like any woman who chooses abortion, I value the right to privacy. But privacy is a tricky and limited business; its byproducts can be loneliness, silence and shame. Perhaps the one third of American women who choose abortion before age 45 can use a little less privacy, and a little more solidarity. That’s why, two years after my abortion, I offer my story.

For me abortion was the way forward. It was also the roughest decision I’ve ever made. But it was my own rough decision. So on the anniversary of Roe v. Wade, I defend the right to choose in what ways, when and with whom we create life.