The section 'Baby born in or before the QW' has been updated in the Statutory Maternity Pay guidance to help clarify the average weekly earnings in the relevant period.
If the baby’s born before or during the QW (qualifying week), the continuous employment rule is satisfied if they would have completed 26 weeks continuous employment with you had it not been for the baby’s early birth.
You must work out the AWE (average weekly earnings) in the relevant period by using the birth date instead of the QW.
Further guidance can be found in Statutory Maternity Pay: employee circumstances that affect payment.