It seems to me, first of all, from what I understand from doctors, that's really rare. If it's a legitimate rape, the female body has ways to try to shut that whole thing down.
There are a number of subtle and sensitive issues involved but Akins stomped on all of them with jackboots. Even if we assume that he meant "violent rape" instead of "legitimate rape" he is still wrong. There are no biological mechanisms that prevent pregnancy in these cases. It is true that pregnancy from rape is rare but it does happen.
There are three basic camps in the abortion debate. There are the pro-abortion people led by the feminist movement. To them, all unplanned pregnancies should be terminated immediately as well as any planned pregnancies where the mother has any doubts. As far as this group is concerned, a fetus is not a person and has no rights until it is born.
The middle ground is populated be people who think that abortion should be legal but recognize that there is more to the procedure than removing an unwanted growth. This group is uncomfortable with abortion and sees no problem with things such as a waiting period or requiring parental permission (with allowances for judicial override) for minors.
The third group is against abortion period. Many will make an exception for incest or rape but some would allow no exceptions, ever. Obviously Akins is in this last group. His assertion about rape is an attempt to justify an extreme position and puts the extra stigma on rape victims that if they got pregnant then they weren't really raped. Akins's critics are justified in calling this medieval thinking.
Mitt Romney is against abortion although he allows exceptions. He used to be in the middle group and his change gave rise to complaints of him being a flip-flopper on major issues.
During the primaries, Rick Santorum's extreme views on birth control allowed Democrats to declare that the Republicans have waged a "war on women". Akins has allowed them to revive this slogan and to try to link it with Romney.
Romney has denounced Akins, beating President Obama to it by several hours.
Akins still does not seem to realize what he did and how much trouble he caused for all Republicans. So far he has mainly apologized for the use of the word "legitimate". The party has cut him off from all funding and is urging him to withdraw from the race. Akins vows to continue the race and the deadline for withdrawing is today.
Akins should withdraw. His presence hurts all Republicans.
Sidenote, the definition of rape has become a politically charged topic all on its own. Feminists have diluted the term so that it includes acts that were consensual at the time but the woman later has "buyer's remorse". College campuses have instituted rules that almost require consenting students to sign release forms with witnesses.
But that is a subject for a different post.