Compile the essential information about your seven-month old child in list form. Decide what is important and what is not by imagining that this statement is the only chance the readers will get to "meet" your child. The information that you include will be the only means by which the reader can come to a conclusion about the child but the statement still must be brief -- one paragraph.
Look over the list that you have compiled and decide what will go into your final product. Perhaps you have included that your child loves bananas and is afraid of cats. Maybe you have also included your child's first several words. Scale your information down by only including the first word that your child spoke or do not include what she wears on a daily basis as that is not her choice quite yet.
Write your abstract in sentence form with the most important information at the beginning, and the less important toward the end. If you find that you have included facts that are no longer relevant, delete them. Have someone proofread your abstract for you to catch any grammatical or spelling errors.