Why Does Pregnancy Make You Pee So Often?

I felt so bad earlier took my son to the park to ride his bike and within 20 minutes I had to pee so bad . I go see if the bathrooms are open at the park and they are closed and it felt like I was going to explode especially with all the pressure down there.
Had to go home he was kinda bummed but he understood I was really upset can't really go out at this point alot I enjoy being home.
With that said isn't it crazy how a little bit of urine comes out when you do go like really lol every 20 to 30 minutes I gotta pee! Ugh Can't wait till this is over.