I suppose it just means that its lack and the baby can move more freely instead of being tight where the baby is restricted.My baby moves alot too and when i went to have the heart listened too the Midwife had to chase this active baby about all over my stomach and took 10 minutes before actually getting to listen to the heartbeat and as listening to it the monitor she was using got kicked about abit and the reply was "wow active baby",so i must have the same as you.