The friends are speed bumps because you may have to put your professional life in second place now and then to make time for friends, just like you have to slow down for speed bumps. Your post seems to say that having friends is bad, but to me, the part about friends being speed bumps brings to mind the more popular phrase slow down and smell the roses. When you really think about it, if friends are speed bumps, and you don't find any speed bumps on the road to success, are you sure you're going the right way?
You can be fired for any reason, just as you can quit for any reason. If you were fired for an UNLAWFUL reason, you can file an administrative discrimination complaint (not a lawsuit) and the employer has the burden of proving there was ANY LAWFUL reason to dismiss you, such as your inability to do the job (unrelated to the pregnancy). If they win on that one, and you have exhausted your administrative remedies, THEN you can sue them for wrongful termination. Courts don't generally want to get involved in administrative issues, but rather resolve those few that don't clearly fit within lawful administrative rules. Your mileage may vary. A simple phone call to a law firm dealing in employment litigation may get you a free consultation to determine what legal avenues are open to you, under your particular circumstances and your state laws (or even federal laws, if your employer comes within federal jurisdiction).