You must give your employer medical evidence of the date your baby is due. This will normally be on a maternity certificate (MATB1) that you can get from your doctor or midwife. You cannot get this certificate until you reach the 20th week before the week in which your baby is due (generally the 21st week of pregnancy). Your doctor or midwife will usually give you the MATB1 at your next antenatal appointment after then.
Your employer may be willing to accept other medical evidence, but this must be broadly the same as a maternity certificate. It must be in writing, it must identify you, it must be issued by your doctor or midwife no more than 20 weeks before the week the baby is due, and it must either be stamped with your doctor’s name and address, or show your midwife’s name and personal identity number.
Schools’ Choice will now accept copies of MATB1s from employees and do not have to see the original.
You can find a detailed guide on Maternity Benefits here.