An increase in swayback posture can cause stress on the facet joints in your spine. (coreexercisesolutions.com)
Overactive / short internal obliques can also contribute swayback posture. (kingofthegym.com)
There appears to be a lot of different opinions on the internet with swayback being referred to as lordosis or a more extreme form of lordosis, it is important you know the difference so you are not making the problem worse — Do you know if you have an anterior pelvic tilt or a posterior pelvic tilt? (fitbodyhq.com)