Abortion rates have been falling over the years. The Centers for Disease Control and Prevention (CDC) completed a study last year that analyzed long-term abortion trends, spanning from 1969 to 2011.

The CDC counted 730K+ abortions in 2011, which works out to 16.9 abortions per 1K women ages 15-44. This is the lowest ratio for abortions since 1973, where 16.3 abortions were recorded for every 1K women within the aforementioned age range. The study’s abstract notes that abortions were highest among adolescents and lowest among women ages 30-39 for the duration of the study. Women in their 20s had the majority of abortions.

Researchers speculate that the decrease in abortions is linked to changing social attitudes about the practice, as well as marriage. When marriage was the socially-acceptable default setting for relationships, abortions were much more rare. But now that marriage rates have decreased, many women are choosing to terminate an unplanned pregnancy rather than have a shotgun wedding with the father.

An article on “The Atlantic” also notes that American attitudes toward abortion have shifted in recent years. While only 20% of the surveyed population would like to see the practice outlawed, 38% surveyed believe it’s “morally objectionable.” This prevailing idea is likely preventing some women from having abortions, and so carrying the fetus the term. It’s very possible that the numbers on abortion are higher than reported, due to any lingering shame or stigma (either internal or external) women who’ve gone through it may face.