When it comes to pregnancy, medical advancement has given parents welcome choices never before considered. At the same time, it’s created a new landscape of ethical dilemmas, for individual parents and for the public.

A couple of recent examples: Tests are now available on the U.S. market that can tell a pregnant woman the sex of her embryo as early as seven weeks, raising the specter that couples may practice gender selection; others are being developed to test for Down syndrome at nine weeks, increasing the likelihood of parents choosing to abort.

Ruth Padawer was inspired to write her story “The Two-Minus-One Pregnancy” after reading "Everything Conceivable," by Post reporter Liza Mundy. (Amazon.com)

Padawer’s New York Times Magazine cover story chronicled the increasing number of pregnant women who are “reducing” their twin pregnancies to single pregnancies.

Here’s an excerpt:

“What is it about terminating half a twin pregnancy that seems more controversial than reducing triplets to twins or aborting a single fetus? After all, the math’s the same either way: one fewer fetus. Perhaps it’s because twin reduction (unlike abortion) involves selecting one fetus over another, when either one is equally wanted. Perhaps it’s our culture’s idealized notion of twins as lifelong soul mates, two halves of one whole. Or perhaps it’s because the desire for more choices conflicts with our discomfort about meddling with ever more aspects of reproduction.”

I asked Padawer, a mother of twins herself, to share the back story to “The Two-Minus-One Pregnancy.”

Q. What inspired you to research and write about the topic?

A. I first heard about pregnancy reduction back in the late 1980s, when it was being used to reduce pregnancies of six, seven, eight fetuses to twins or triplets. I’ve been curious about it ever since, not just what it was like for the pregnant woman but also how it fit into society’s relationship with rapidly expanding reproductive options.

Several years ago, I began hearing from doctors that more women were reducing from two to one. I subsequently read “Everything Conceivable,” by Washington Post writer Liza Mundy. It’s a fabulous, thought-provoking book that noted that some doctors reduce from twins to one. I decided earlier this year that I wanted to explore that development more, so I reported and wrote this article.

Q. What was the most surprising thing you learned along the way?

A. That’s a hard question to answer. I learned so much. Two things intrigued me most: One, that two-to-one reduction is, in some ways, more controversial than aborting a whole pregnancy. And two, that having so many choices (a seemingly liberating thing) can also create very difficult burdens. I decided to focus the article on those two things.

Q.What’s your reaction to the feedback?

A. My aim in writing the article was to look at this development from many perspectives, each compelling in its own way.  I’d hoped to get past the knee-jerk reactions and rhetorical noise, to prompt a more nuanced and respectful conversation. I’ve been uncomfortable with the vitriol in some online comments, especially toward a woman at the beginning of the article named Jenny.

Like most women who reduce two to one, Jenny was in her late 40s, already had kids, used [in vitro fertilization] and donor eggs because she wanted another child, and was terrified of having more than one baby. I knew plenty of readers would disagree with her choices, which is fine. But I hoped that readers would nonetheless understand the emotions that drove the decision: the desire, even the pressure, to make all the right choices (whatever she determined them to be) so she could be (by her reckoning) the best mom for her kids.

On the other hand, many of the other online comments and virtually all the e-mails I’ve gotten from readers have been thoughtful and honest and sometimes quite moving. People who identify as “pro-life” and people who identify as “pro-choice” have described how, in a very visceral way, they can now see the issue from the other point of view. That makes me hopeful.