The answer is very simply, yes. Social media posts can negatively affect basically all times of litigation, including personal injury cases, like auto accidents or wrongful death claims; criminal defense cases; and family law cases, like divorce or custody disputes.
The information you post online is not confidential or protected. That information can be used in your case against you OR by another person suing you. As time progresses it becomes more likely that information WILL be used against you.
As more people use social media, such as Facebook and Twitter, legal opponents often review your accounts for evidence to use against you in your case. Or to support their own case. If you think about it, it makes sense. Today people disclose tons of personal and even intimate information online. And that information can be used against you in your case. If you know you have a legal dispute ongoing, the best advice is to stop posting anything on social media until your lawyer tells you otherwise. Also make sure your privacy setting are on the highest possible setting.
It is difficult to know all the ways that social media can negatively affect your case. Whether it is for an injury you suffered or to determine custody and visitation of your child. With that in mind it is best to always use judgment on what you post online. And stop using social media until your lawsuit has concluded.