BIRTHS TO UNMARRIED MOTHERS ARE at a record high in the United States--almost 1.5 million in 2004 alone, according to the National Center for Health Statistics. While the rising trend is of long standing, one novel factor driving up childbearing outside marriage is the growing popularity of single motherhood by donor insemination. The incidence of this "assisted reproduction," as it is called, has more than doubled in the last decade.

Most public discussion of donor insemination for single women has been carried on in a neutral, positive, or breathlessly celebratory tone. Isn't it great, the thinking seems to be, that these women are fulfilling their aspiration to be mothers with the latest technology that medical science can offer? Support groups like Single Mothers by Choice and mainstream publications like the Atlantic Monthly, the New York Times, and the Washington Post describe donor insemination for unmarried mothers occasionally as a "sad" necessity for women who cannot find "satisfactory" partners, but more often as "awe"-inspiring, "liberating," or "empowering." Television shows like NBC's drama Inconceivable, broadcast this fall, glamorize assisted reproduction.

This enthusiasm is notable at a time when European countries are skeptical enough to actually ban the process. Sweden and Italy bar single mothers from engaging in either in vitro fertilization or use of anonymous sperm (or, in Italy, eggs), and Britain and the Netherlands have banned the anonymous donation of sperm. Also striking is how adult-centered our public conversation has been. Until recently, virtually no attention was paid to how the children of donor

But there are good reasons to worry about this latest manifestation of fatherlessness. Listening directly to the voices of donor-conceived children should give us pause. Kyle Pruett, a psychiatrist working at the Yale Child Study Center, reports in a recent book that such children have an unmet "hunger for an abiding paternal presence." He quotes one girl as saying, "Mommy, what did you do with my daddy? You know I need a daddy or I can't be a child." A story in the New York Times last month reported that donor-conceived children check out strange men to see if they match the physical traits of their donor dads. "It'll always run through my mind whether he meets the criteria to be my dad or not," said JoEllen, a girl from Russell, Pennsylvania.

Young adults voice similar sentiments. Olivia Pratten, a 23-year-old Canadian conceived through donor insemination, told the Toronto Globe and Mail about her fatherless life: "I had to grieve. It wasn't till I was 17 or 18 that I got it. I felt very angry. How dare someone take my choice away from me? How dare the medical profession tell me it doesn't matter?" And a 15-year-old boy profiled recently in the New Scientist was so determined to find his father that he submitted a sample of his own DNA to an online DNA-testing service. He was able to match it to a family surname and from there to track down his dad. Young people with less ingenuity are probably out of luck. U.S. law does not regulate donor insemination, and most donors choose anonymity, making it very difficult to find them.