Of American-English origin, the male-chauvinistic phrase barefoot(ed) and pregnant, also pregnant and barefoot(ed), means that the place of women is in the home and that their role is to bear children.

The earliest occurrence that I have found is from The Horse and Buggy Doctor (New York and London: Harper and Brothers, 1938), the autobiography of the U.S. physician Arthur E. Hertzler (1870-1946):

Some vulgar person has said that when the wife is kept barefooted and pregnant there are no divorces. Bad as this sounds, it is so because it is so near the truth; but it does not fit into our growing notion of what constitutes civilized society.

The second-earliest occurrence that I have found is from One Man’s Opinion, by the Canadian columnist Richard J. Needham (1912-1996), published in The Calgary Herald (Calgary, Alberta) of Friday 11^th June 1943—Needham presents the phrase as “an old American witticism”:

For generations, the women of Canada and the United States have been told, by word and by action, that they were inferior beings and that their place was in the home. They have been told it over and over again by the church, by politicians, by men—and by women. They have been and are discriminated against in a million ways because they happened to be born female. They have been and are paid lower wages than men for doing the same work with the same skill […].
Woman’s place is in the home. Hitler ¹ says so: popular tradition in Canada and the United States agrees with him, giving them the outward appearances of freedom, but actually doing everything possible to keep them tied down to the Nazi formula: kitchen, church, children. “Women should be kept clean and illiterate, like canaries,” said a character in the picture “Woman of the Year,” ² and the movie house rocked with laughter and applause. An old American witticism puts it more tersely: “Keep ’em barefoot and pregnant.”

¹ The Austrian-born Nazi leader Adolf Hitler (1889-1945) was Chancellor of Germany from 1933 to 1945.
² Woman of the Year (1942) is a U.S. comedy-drama film directed by George Stevens (1904-1975), starring Katharine Hepburn (1907-2003) and Spencer Tracy (1900-1967). The plot centres on Tess Harding—an international affairs correspondent, chosen “Woman of the Year”—and Sam Craig—a sportswriter—who meet, marry and encounter problems as a result of her unflinching commitment to her work.

Private First Class William Land, of Baton Rouge, used the phrase—in quotation marks—as a literal description of the women of Okinawa, in southern Japan, in an article published in the State Times Advocate (Baton Rouge, Louisiana) of Thursday 30^th August 1945—this article was originally published, under the title Fighting Men With Tender Hearts: GIs Play Nurse To Oki’s Orphans, in The Stars and Stripes: U.S. Armed Forces Daily In The Pacific Ocean Areas of Tuesday 22^nd May 1945:

Okinawa—Here’s a story you could call “The Children’s Hour.” Ever since I got that radio about my new baby daughter, I’ve had in mind writing a children’s story, especially since the material is so plentiful.
It is said that there are more children on Okinawa than there are goats, and, brother, that is some statement.
Very rarely does one see a woman who isn’t carrying either a born or unborn child around and most of the time its [sic] both.
“Barefoot and pregnant” seems the fashion in Okinawa society.
For doughboys and leathernecks, the care of children started on the first day of the invasion, and from the way it keeps on, it looks as though “The Children’s Hour on Okinawa” will outlast Lillian Hellman’s play on Broadway. ³
Military government has even set up an orphanage, probably the first the island has seen.

³ The Children’s Hour (1934) is a stage play by the U.S. dramatist and screenwriter Lillian Hellman (1905-1984).

In 1948, one Christine Johnston took legal action against James Folsom (1908-1987), then Governor of Alabama, in order to establish paternity of her son and be recognised as his common-law wife. One of the 264 questions contained in the interrogatory filed by Johnston’s counsel was whether Folsom said to one Billy Pichelmayer:

– According to a United-Press report dated Saturday 8^th May 1948, published the following day in the Daily News (New York City, N.Y.):

“Billy, us men ought to keep our wives barefooted and pregnant.”

– According to a United-Press report dated Wednesday 12^th May 1948, published the following day in The News and Observer (Raleigh, North Carolina):

“Billy, us men ought to keep our women barefoot and pregnant.”

The phrase occurs in this extract from What hath God Wrought? America’s petted, idolized glamour girl gets shoved from her pedestal in the first of a series by the ace hydrochloric columnist, Robert C. Ruark, published in Esquire: The Magazine for Men (Chicago: Esquire, Inc.) of October 1950:

I never bought that old axiom about keeping ’em pregnant and barefooted, in order to insure peace in the dovecote, and even came out, once, in favor of letting women eat at the same table with the menfolk. Time has proved me wrong. The initial mistake was made in treating women like people. We did them no favor when we allowed them the rights and privileges of the male, while subjecting them to few of the penalties of masculinity. Crammed with propaganda and still giddy from political emancipation, Madame Housewife has got entirely too big for her panty girdle. I even recall a note from a couple of years back saying that Ronald Reagan ⁴ and Jane Wyman ⁵ had been divorced, after eight years of marriage, for “political” differences. Nowhere in  marriage ceremony will you find  clause which says “love, honor, cherish and vote the straight Democratic and/or Republican ticket.”

⁴ The Republican statesman Ronald Wilson Reagan (1911-2004) was the 40^th President of the USA from 1981 to 1989. He was a Hollywood actor before entering politics.
⁵ Jane Wyman (Sarah Jane Mayfield – 1917-2007) was a U.S. actress, singer, dancer and philanthropist.

The phrase has been borrowed into British English. However, curiously, the text in which occurs the earliest use that I have found presents the phrase as typical of Englishmen—this text is Simply improving on nature, by the Irish journalist Mary Holland (1935-2004), published in The Observer (London, England) of Sunday 15^th March 1964:

I was once told by a man, and he was not joking, that women are really happy only in their natural state: “barefoot, pregnant and in the kitchen.” He was, need I say, English and like many other Englishmen he was always on about women being natural.