Uk people

Hi at the minute im getting maternity allowance from the goverment because i didnt earn enough for statutory from employee...i been getting it since my princess was born sleeping 14 weeks ago and should return too work may 9th 2015 up until now i been getting the same payments fortnightly but just checked my payment which went in on friday and its 50 pound less then normal....just wondering if any one knows if it goes down as i cant remember being told this x