This is one of the most divisive topics in modern politics. Most people have very strong opinions on it whether positive or negative so that no matter what you choose to write, you will need to be prepared to offend someone. If your stance is that the practice is wrong, here are some steps you can follow in writing your essay.
Omitting this step is a common mistake. There are people who refer to the Plan B or morning after pill as a means of abortion when what it actually does is prevent the egg from being fertilized after copulation but before the sperm reach the egg. There are various methods for terminating a pregnancy depending on how far along it is. You need to research these to include a clear description that is not purely emotional. Also remember to clarify that miscarriages do occur and are not intentional.
A fertilized egg is genetically human whether or not everyone can agree to its ‘personhood’ as yet. You should look for evidence that shows the extent to which a zygote or a fetus should be accorded human rights just as any other human.
Most of the people who consider themselves pro-life are in part motivated by their religious beliefs to think so. Look at the religious texts to find views that support what you outline in your paper.
You can look for the options that unprepared parents have to help them raise the baby if they decide not to abort. Compiling a good list of options weakens the argument that safe abortions are necessary to society in some way.
If you intend to write an essay that stands up to scrutiny from people on both sides, you should address some difficult arguments that the pro-choice advocates will put forward. What should be done in cases where the pregnancy risks the mother’s life? Should parents carry babies to term that have been tested and found to be severely ill with very short life spans after birth? Should victims of rape and incest (particularly those that are under-aged) be made to carry their rapist’s baby to term? If you can give a balanced and factual response to these questions your writing will be very persuasive to anyone.