Today we grow concerned about birth not being natural enough, having become too medical. Historically it was thoroughly natural, wholly unmedical, and gravely dangerous.

Eds. note: This story was updated at 5:30 p.m. with additional quotes from Adamczyk.

The killing of an abortion provider on Sunday raises again the extreme potential consequences of the nation's schism on this topic. It's a tough issue to reconcile on a personal level too, and a new study on the effects of religiosity on the decision to have an abortion reveals more inconsistencies.

Unwed pregnant teens and 20-somethings who attend or have graduated from private religious schools are more likely to obtain abortions than their peers from public schools, according to research in the June issue of the Journal of Health and Social Behavior.

"This research suggests that young, unmarried women are confronted with a number of social, financial and health-related factors that can make it difficult for them to act according to religious values when deciding whether to keep or abort a pregnancy," said the study’s author, sociologist Amy Adamczyk of John Jay College of Criminal Justice and the Graduate Center, City University of New York.

(George Tiller, a 67-year-old physician who had long been targeted by anti-abortion activists, was shot and killed Sunday while attending church in Wichita, Kan.)

Adamczyk examined how personal religious involvement, schoolmate religious involvement and school type influenced the pregnancy decisions of a sample of 1,504 unmarried and never-divorced women age 26 and younger from 125 different schools. The women ranged in age from 14 to 26 at the time they discovered they were pregnant. Twenty-five percent of women in the sample reported having an abortion, a likely underestimate, Adamczyk said.

As a group, the women in Adamczyk's sample are less likely to abide by their religious beliefs, she said. "They have already had premarital sex, and women who are engaging in riskier sex behaviers (i.e. more partners, a one-night stand, etc.) are more likely to end up in the predicment of being pregnant and unmarried," she said.

"However, when faced with this incredible decision, things like education and future aspiriations simply appear to matter more," Adamczyk told LiveScience. Later in life, women might be more inclined to carry a pregnancy to term, perhaps for religious reasons, she said. Religion might have a greater influence on one's decisions when school and career aspirations have already been achieved or are moving along well.

Results revealed no significant link between a young woman's reported decision to have an abortion and her personal religiosity, as defined by her religious involvement, frequency of prayer and perception of religion's importance. Adamczyk said that this may be partially explained by the evidence that personal religiosity delays the timing of first sex, thereby shortening the period of time in which religious women are sexually active outside of marriage.

Despite the absence of a link between personal religious devotion and abortion, religious affiliation did have some important influence. Adamczyk found that conservative Protestants (which includes evangelicals and fundamentalist Christians) were the least likely to report having an abortion, less likely than mainline Protestants, Catholics and women with non-Christian religious affiliations.

"On the other hand, simply attending church or finding religion important does not appear to shape a young unmarried woman's abortion decisions," Adamczyk said. "But many very liberal-minded people who seem themselves as prochoice still attend church."

Regarding the impact of the religious involvement of a woman's peers, Adamczyk found no significant influence. However, Adamczyk did find that women who attended school with conservative Protestants were more likely to decide to have an extramarital baby in their 20s than in their teenage years.

"The values of conservative Protestant classmates seem to have an abortion limiting effect on women in their 20s, but not in their teens, presumably because the educational and economic costs of motherhood are reduced as young women grow older," Adamczyk said.

Despite Adamczyk's finding that rates of reported abortions were higher for young women educated at private religious schools, the type of religious school was not a factor: Catholic schools had similar rates as other religious schools.

"Religious school attendance is not necessarily indicative of conservative religious beliefs because students attend these schools for a variety of reasons," Adamczyk said. "These schools tend to generate high levels of commitment and strong social ties among their students and families, so abortion rates could be higher due to the potential for increased feelings of shame related to an extramarital birth."

Data for this study came from the National Longitudinal Study of Adolescent Health (Add Health), a three-wave school-based study of the health-related behaviors of students in grades 7 to 12 at the time of the first wave. Adamczyk analyzed data from the first and third waves of Add Health, the first wave taking place from 1994 to 1995 and the third wave being completed between 2001 and 2002. The Add Health program project was funded by the National Institute of Child Health and Human Development, along with several other agencies.