My ethical decisions to lay-off those three workers would be based on utilitarian approach that blends economic theory with philosophy.  John Stuart Mill and Jeremy Bentham are the persons who are identified with developing utilitarian thinking (Boathright, 2003).  Mill's assumption was that pleasure leads to happiness and that pain takes away happiness.  Utilitarianism states that the most ethical thing to do is bring the greatest amount of happiness and pleasure to the greatest number of people.  Moral decisions are based on what is best for the entire community.  For example, in this case 3 people are to be laid off, but the company is saved from bankruptcy and 9 people keep their jobs.  The happiness and pleasure of the group of 9 is greater than the pain suffered by the 3 who lost their jobs.
 
To lay off the three workers, I would inform all employees of the pending company decision to reduce the work force. Having moral alternatives in mind: The pregnant employee can be reduced to part-time basis and eventually given leave of absence with pay and terminated if the company does not recover (a gradual process). The employee close to retirement would be given early-retirement. And my close friend would be considered for redeployment or give employee assistance package as a last resort and also keep options open for new business adventures. Somewhere down the line you have to be bold and say, “sorry due to the financial problems and other factors the company is not doing well and we have to let you go.”

Utilitarianism also advocates or favor government regulations to protect workers so that employers do not exploit them as opposed to Kant’s assume the risk philosophy (Boathright, 2003).

Considering other theories to apply in case: The rights and duties theory analysis shows that workers have no real right to a job and the owners have a duty to shareholders. This leads to the conclusion that managers indeed sometimes have a duty to conduct layoffs, and in fact it would be unethical not to lay off workers in some instances. However, it would have been difficult to prove that managers have a duty to do a layoff in the case of an already well performing company. The justice and fairness theory issue fails because no matter how you lay off a portion of the workers, it is not proportional and consistent.  A worker who is doing well, yet is fired is not treated in a proportionate way. Laying-off some workers and not other similar workers is not consistent.

Utilitarianism concludes that the greatest good for the greatest number of people is not to lay off workers in the case of a well performing company. So in this case it’s ethical because the company is not performing well. If the layoffs were to just improve performance then the utilitarian position would be that it is unethical. It’s not a moral thing to layoff workers but the Utilitarian approach to lay-off in this case is the best way to go.

Reference:
Boatright, John R. (2003). Ethics and The Conduct of Business. Upper Saddle River:
                  Prentice Hall