A woman taking maternity leave is generally entitled to 90% of her full pay for the first six weeks. This is broadly based on the earnings in the fifth and sixth months of pregnancy. A pay rise coming into effect later than this is not taken into account.
The European Court of Justice has ruled that the UK method of calculating maternity pay is discriminatory and therefore unlawful. A pay rise even if outside this period should be taken into account so long as it came into effect before the end of the period of paid maternity leave. The decision could mean that women who have taken maternity leave and failed to get relevant pay rises taken into account will be able to claim what they are owed.