how to print ps header when using pipe in linux

how to print ps header when using pipe in linux

this normal ps output

$ ps -ef
UID         PID   PPID  C STIME TTY          TIME CMD
root          1      0  0 17:00 ?        00:00:02 /usr/lib/systemd/systemd

but below ps command output without header

$ ps -ef | grep systemd
root          1      0  0 17:00 ?        00:00:02 /usr/lib/systemd/systemd

how do i print ps header for second command?

thx