Consider apologizing or acknowledging the situation afterward.

Since you noticed the woman was moved to business class, it could have been a chance to follow up with either the flight attendants or the woman herself afterward. A simple apology or acknowledgment of her discomfort could have turned the situation into one of mutual understanding.
Even if the incident was brief, this small gesture might have had a big impact on how both of you perceived the situation later on.
Understand the power of the flight attendant’s role.

While it may have seemed unfair to have the woman moved, flight attendants are trained to handle conflicts and prioritize the comfort of all passengers. You might want to see this as a reminder of the crucial role they play in maintaining harmony on the flight.
Rather than viewing the situation as a direct infringement on your rights, try to see their intervention as an effort to create a more pleasant environment for everyone, yourself included.
Use this experience as a chance to grow in future interactions.
Reflecting on the situation, you might view it as an opportunity to handle similar scenarios differently next time. While you were within your rights to recline your seat, this experience could help you recognize how personal circumstances—like pregnancy—can influence someone’s comfort in ways you may not immediately see.
In future flights, whether it’s reclining your seat or making other choices, taking a moment to consider how your actions might affect others can help avoid conflicts and make the journey more enjoyable for everyone.