Dear beauties! Anyone with braces and 6+ months pregnant ??

So I’ve been having braces for over a year and now I’m 31 weeks 4 days pregnant and my dentist says my teeth won’t move back or the gaps won’t fill after 6 months of pregnancy until the baby is born so I just need to keep them on my teeth with no adjustments or any work !! Lol never heard of anything like this .. is my ortho right ? Anyone experienced it ?? I still haven’t told him I’m 31 + weeks pregnant he keeps asking me if it’s 6 months yet .... anyone experienced similar problems ? Please help me with this