What is the proper course of action for a pregnant wife, married for less than a year, who discovers her husband's conversations with foreign women?

One must realize that this worldly life is inherently fraught with problems, and the fortunate one is he who accustoms himself to enduring hardships and strengthens his faith in Allah, surrendering to Him. The greatest advice that can be given to one who is distressed is to cultivate inner strength and unwavering resolve, which are acquired through learning and contemplating the lives of the righteous. For if the love of Allah engrosses a Muslim's heart, all problems will become insignificant to him.

As for your specific problem, it is temporary and fleeting. It can be addressed by seeking everything that improves your relationship with your husband to increase his emotional balance, showing care for him, and exchanging kind words. You should also frankly discuss the matter with him calmly, remind him of the fear of Allah, explain the sanctity of what he is doing, while demonstrating forgiveness and clemency. It is imperative to maintain discretion and secrecy, and not to spy on him, for "indeed, gentleness is not in anything but that it adorns it, and it is not removed from anything but that it disgraces it." Perhaps the child you are carrying will be a cause for increased affection, so do not tire of supplicating for him and for yourself for guidance and success.