The CDC gets its data on the number of abortions from state public health departments; the reporting is completely voluntary. Some states, like California, don't report the number of abortions at all.
"In contrast to most important health indicators — births, deaths, cancer, HIV, STDs, etc. — there is no national reporting law requiring that abortions or their complications be reported to national health officials or agencies. Americans United for Life, the legal architects of the pro-life movement, has model legislation that can address this egregious void in our public health systems, as well as legislation that would require women and girls be given all the information available before having an abortion or taking a life-ending drug."
"It is irresponsible of the President to insist that Americans pay for life-ending drugs and devices as well as for a medical procedure without also requiring a full reporting of the consequences of such a choice. This nonchalance about deaths and complications from a procedure performed routinely on American women is unconscionable."
SOURCE Americans United for Life