Mr Farage, who worked in finance before politics, told an audience in the City that women make "different choices" to men for "biological reasons".
Those taking time off to have children were less valuable to employers on their return, he said.
But discrimination against women in the City was a thing of the past, he added.
Brokers are "as valuable as the client base that sticks with you and will move with you", he explained.
"In many, many cases, women make different choices in life to the ones that men make simply for biological reasons," he said.
"If a woman has a client base and has a child and takes two or three years off work, she is worth far less to the employer when she comes back than when she goes away because her client base cannot be stuck rigidly to her."
When he first started work in the City, it was a "deeply sexist" place, he added.
"I don't believe that in the big banks and brokerage houses and Lloyds of London and everyone else in the City, I do not believe there is any discrimination against women at all.
"I think that young, able women who are prepared to sacrifice the family life and stick with their careers do as well, if not better, than men."
Mr Farage elaborated on BBC Radio 4's The World at One: "People who bring in commission business are people who've worked very closely with clients, over years and years and years.
"If you have children and take nine months, or a year, or maybe more off, you tend to lose some of that business.
"I think the reality for women in the City is that if they have children, it has a very detrimental effect on their future pay prospects."
He was asked whether it should it be this way.
"I can't change biology," he replied.
Women prepared to sacrifice family life can do as well as male colleagues in financial firms, if not better, UKIP leader Nigel Farage has said.