Uncomfortable Sex?

🎀Nina🎀 • FTM due January 2, 2017 with Little Miss Lanza
Hey ladies! I'm currently 21 weeks & just wondering when does sex become uncomfortable. At the moment it's just certain positions it's uncomfortable bc of my stomach. But it's still something I can tolerate for now (if that makes any sense). But my question is when does it become something I can no longer tolerate? Or just too uncomfortable? I understand everyone is different but I'm just curious.