The gender pay gap is widest when a woman reaches 50, at an average of more than £8,400 a year, according to a new study.
Full-time female workers are paid less than men at every stage of their career from when they turn 18, research by the TUC showed.
The average 18 to 21-year-old woman working full-time starts her career on the back foot financially, earning £1,845 less than her male peers, it was found.
The gap widens to more than £2,300 for 22 to 29-year-olds, and leaps from £3,670 a year at the age of 30 to £7,400 a year for women in their 40s, said the union organisation.
The TUC said this reflected the impact of motherhood on women’s earnings, when women find they are only able to return to work in lower-paid roles or cannot progress their careers after having moved to part-time employment.
General secretary Frances O’Grady said: “Women suffer a huge pay penalty over the course of their lives, starting as soon as they set foot on the career ladder.
“Having children and caring responsibilities has a massive impact on a woman’s earnings. Far more needs to be done to help mums get back into decent, well-paid jobs after they have kids - and to encourage dads to take on their share of caring responsibilities.”