When to inform employer of pregnancy?

[July2015]

Hello,

I'm 21 weeks pregnant (due 31st July). When is the 'deadline' for when I have to legally inform my employer of my pregnancy?

Thanks

By 25 weeks - it's phrased as 15 weeks before the baby is due.

As the above poster says, by 25 weeks, you should get your MAT1B form from the midwife at this point to give them. Personally I told them at 12 weeks to give them time to plan, then formalised with HR when I got my MAT1B.

Brilliant, thanks both!

I told my manager at 5 weeks as I needed a risk assessment due to manual handling. I also had to have a workstation assessment. I am 25w on Sunday and need to do another risk assessment.
I am the size of a house and had a definite bump from 10w and it didn't go unnoticed by the other staff, although officially told my colleagues afetr the 12w scan.
For maternity leave purposes as the other posters stated, it is 25w when you have to give in your MATB1 form, although I had to go through the mat leave policy with my manager the week before.