Life
Sanger was born in Corning, New York. Her mother was a devout Roman Catholic who went through 18 pregnancies (with 11 live births) before dying of tuberculosis. After graduating from Claverack College in Hudson, Sanger trained as a nurse and worked for ten years in the affluent New York suburb of White Plains. In 1902, she married William Sanger. Although stricken by tuberculosis, she gave birth to a son the following year, followed in subsequent years by a second son and a daughter who died in childhood.

In 1912, Sanger and her family moved to New York City, where she went to work in the poverty-stricken East Side slums of Manhattan. That same year, she also started writing a column for the New York Call entitled "What Every Girl Should Know." Distributing a pamphlet, Family Limitation, to poor women, Sanger repeatedly risked scandal and imprisonment by acting in defiance of the Comstock Law of 1873 which outlawed as obscene the dissemination of contraceptive information and devices.

In 1914, Sanger launched The Woman Rebel, a newspaper advocating birth control. She also separated from William Sanger in 1913. In 1916, Sanger opened a family planning and birth control clinic in the Brownsville neighborhood of Brooklyn, the first of its kind in the United States. It was raided by the police and Sanger was arrested for violating the post office's obscenity laws by sending birth control information by mail.

Sanger fled to Europe to escape prosecution. There, she had an affair with the famous science-fiction author, H. G. Wells. The following year, she returned to the U.S. and resumed her activities, launching the periodical The Birth Control Review and Birth Control News. She also contributed articles on health for the Socialist Party paper, The Call.

In 1916, Sanger published "What Every Girl Should Know," which was later widely distributed as one of the E. Haldeman-Julius "Little Blue Books." It not only provided basic information about such topics as menstruation, but also promoted an understanding of sexuality in adolescents. It was followed in 1917 by What Every Mother Should Know. That year, Sanger was sent to the workhouse for "creating a public nuisance."

Sanger founded the American Birth Control League (ABCL) in 1921 with Lothrop Stoddard and C. C. Little. In 1922, she traveled to Japan to work with Japanese feminist Kato Shidzue promoting birth control; over the next several years, she would return another six times for this purpose. In this year, she also married oil tycoon James Noah H. Slee. In 1923, under the auspices of the ABCL, she established the Clinical Research Bureau.

It was the first legal birth control clinic in the U.S. (renamed Margaret Sanger Research Bureau in her honor in 1940). That year, she also formed the National Committee on Federal Legislation for Birth Control and served as its president of until its dissolution in 1937 after birth control under medical supervision was legalized in many states. In 1927, Sanger helped organize the first World Population Conference in Geneva.

In 1928, Sanger resigned as the president of the ABCL. Two years later, she became president of the Birth Control International Information Center. In 1937, Sanger became chairperson of the Birth Control Council of America and launched two publications, The Birth Control Review and The Birth Control News. From 1939 to 1942, she was an honorary delegate of the Birth Control Federation of America. From 1952 to 1959, she served as president of the International Planned Parenthood Federation; at the time, the largest private international family planning organization.

During the 1960 presidential elections, Sanger was dismayed by candidate John F. Kennedy's position on birth control (Kennedy did not believe birth control should be a matter of government policy). She threatened to leave the country if Kennedy were elected, but evidently reconsidered after Kennedy won the election.

In the early 1960s, Sanger promoted the use of the newly available birth control pill. She toured Europe, Africa, and Asia, lecturing and helping to establish clinics.

Sanger died in 1966 in Tucson, Arizona at age 87 only a few months after the landmark Griswold v. Connecticut decision, which legalized birth control for married couples in the US. It was the apex of her fifty-year struggle.

Sanger's books include Woman and the New Race (1920), Happiness in Marriage (1926), and an autobiography (1938).

Philosophy
Although Sanger was greatly influenced by her father, a freethinker, her mother's death left her with a deep sense of dissatisfaction concerning her own and society's understanding of women's health and childbirth. She also criticized the censorship of her message about sexuality and contraceptives by the civil and religious authorities, justified on moral grounds, as an effort by men to keep women in submission.

An atheist, Sanger attacked the Christian faith for its opposition to her message, blaming it for obscurantism and insensitivity to women's concerns. Sanger was particularly critical of the lack of awareness of the dangers of and the scarcity of treatment opportunities for venereal disease among women. She claimed that these social ills were the result of the male establishment's intentionally keeping women in ignorance. Sanger also deplored the contemporary absence of regulations requiring registration of people diagnosed with venereal diseases (which she contrasted with mandatory registration of those with infectious diseases such as measles).

Sanger was also an avowed socialist, blaming the evils of contemporary capitalism for the unsatisfactory conditions of the young working-class women. Her views on this issue are evident in the last pages of What Every Girl Should Know.

Psychology of sexuality
While Sanger's understanding of and practical approach to human physiology were progressive for her times, her thoughts on the psychology of human sexuality place her squarely in the pre-Freudian 19th century. Birth control, it would appear, was for her more a means to limit the undesirable side-effects of sex than a way of liberating men and women to enjoy it.

In What Every Girl Should Know, she wrote: "Every normal man and woman has the power to control and direct his sexual impulse. Men and woman who have it in control and constantly use their brain cells thinking deeply, are never sensual." Sexuality, for her, was a kind of weakness, and surmounting it indicated strength:

“Though sex cells are placed in a part of the anatomy for the essential purpose of easily expelling them into the female for the purpose of reproduction, there are other elements in the sexual fluid which are the essence of blood, nerve, brain, and muscle. When redirected in to the building and strengthening of these, we find men or women of the greatest endurance greatest magnetic power. A girl can waste her creative powers by brooding over a love affair to the extent of exhausting her system, with the results not unlike the effects of masturbation and debauchery.”

Her thoughts on human development were also laden with racism:

It is said that a fish as large as a man has a brain no larger than the kernel of an almond. In all fish and reptiles where there is no great brain development, there is also no conscious sexual control. The lower down in the scale of human development we go the less sexual control we find. It is said that the aboriginal Australian, the lowest known species of the human family, just a step higher than the chimpanzee in brain development, has so little sexual control that police authority alone prevents him from obtaining sexual satisfaction on the streets.

Sanger also considered masturbation dangerous:

In my experience as a trained nurse while attending persons afflicted with various and often revolting diseases, no matter what their ailments, I have never found any one so repulsive as the chronic masturbator. It would be difficult not to fill page upon page of heartrending confessions made by young girls, whose lives were blighted by this pernicious habit, always begun so innocently, for even after they have ceased the habit, they find themselves incapable of any relief in the natural act. [...] Perhaps the greatest physical danger to the chronic masturbator is the inability to perform the sexual act naturally.

For her, masturbation was not just a physical act, it was a mental state:

“In the boy or girl past puberty, we find one of the most dangerous forms of masturbation, i.e. mental masturbation, which consists of forming mental pictures, or thinking obscene or voluptuous pictures. This form is considered especially harmful to the brain, for the habit becomes so fixed that it is almost impossible to free the thoughts from lustful pictures.”

Eugenics and Euthanasia
Sanger was a proponent of eugenics, a social philosophy (criticized as a pseudoscience) claiming that human hereditary traits can be improved through social intervention. Methods of social intervention (targeted at those seen as "genetically unfit") advocated by eugenists have included selective breeding, sterilization, and euthanasia. In 1932, for example, Sanger argued for:

A stern and rigid policy of sterilization and segregation to that grade of population whose progeny is already tainted or whose inheritance is such that objectionable traits may be transmitted to offspring.

With advances in biology and genetics, it has become clear that the policies Sanger advocated to prevent the disabled from reproducing would in practice be ineffective. However, in the early 20th century, the eugenics movement, in which Sanger was prominently involved, gained strong support in the United States. As a result of the efforts of American eugenists, "eugenics practitioners coercively sterilized some 60,000 Americans, barred the marriage of thousands, forcibly segregated thousands in 'colonies,' and persecuted untold numbers in ways we are just learning."

It has also been argued that the work of the American eugenics movement was directly responsible for the rise of the Nazi eugenics programs (such as the T-4 Euthanasia Program) and the Holocaust. Edwin Black writes:

Eventually, America’s eugenic movement spread to Germany as well, where it caught the fascination of Adolf Hitler and the Nazi movement... in 1934 the Richmond Times-Dispatch quoted a prominent American eugenicist as saying, "The Germans are beating us at our own game."

Advocates for Mararet Sanger's contend that her eugenic policies tied in with her primary cause of birth control, which she saw as a means to prevent "dysgenic" children from being born and living a disadvantaged life. While many leaders in the eugenics movement were calling for active euthanasia of the "unfit," Sanger did not share such views. Edwin Black writes:

In [William] Robinson's book, Eugenics, Marriage and Birth Control (Practical Eugenics), he advocated gassing the children of the unfit.

In plain words, Robinson insisted: 'The best thing would be to gently chloroform these children or give them a dose of potassium cyanide.' Margaret Sanger was well aware that her fellow birth control advocates were promoting lethal chambers, but she herself rejected the idea completely. 'Nor do we believe,' wrote Sanger in Pivot of Civilization, 'that the community could or should send to the lethal chamber the defective progeny resulting from irresponsible and unintelligent breeding.'

Legacy
Sanger remains a controversial figure. While she is widely credited as a leader of the modern birth control movement, and remains an iconic figure for the American reproductive rights movements, she also is reviled by some who condemn her as "an abortion advocate" (perhaps unfairly so: abortion was illegal during Sanger's lifetime and Planned Parenthood did not then support the procedure or lobby for its legalisation) or those who disagree in principle with Eugenics.

Groups opposed to Planned Parenthood and/or legalized abortion have frequently targeted Sanger for her views, attributing her efforts to promote birth control to a desire to "purify" the human race through eugenics, and even to eliminate minority races by placing birth control clinics in minority neighborhoods. For this reason, Sanger is often quoted selectively or out of context by detractors (a practice known as quote mining), and her history and involvement with socialism and eugenics have often been rationalized or even ignored by her defenders and biographers (a practice known as spin doctoring). Despite the allegations of racism, Sanger's work with minorities earned the respect of civil rights leaders such as Martin Luther King Jr. In their biographical article about Margaret Sanger, Planned Parenthood notes:

In 1930, Sanger opened a family planning clinic in Harlem that sought to enlist support for contraceptive use and to bring the benefits of family planning to women who were denied access to their city's health and social services. Staffed by a black physician and black social worker, the clinic was endorsed by The Amsterdam News (the powerful local newspaper), the Abyssinian Baptist Church, the Urban League, and the black community's elder statesman, W.E.B. DuBois.

Although Sanger's views on abortion (like many of her opinions) changed throughout the course of her life, in her early years she was acutely aware of the problem of abortion, typically self-induced or with the aid of a midwife. Her opposition to abortion stemmed primarily from a concern for the dangers to the mother, and less so from legal concerns or the welfare of the unborn child. She wrote in a 1916 edition of Family Limitation, "no one can doubt that there are times when an abortion is justifiable," though she framed this in the context of her birth control advocacy, adding that "abortions will become unnecessary when care is taken to prevent conception. (Care is) the only cure for abortions." Sanger consistently regarded birth control and abortion as the responsibility and burden first and foremost of women, and as matters of law, medicine and public policy second.

Although the problems of eugenics were not anticipated and Sanger ultimately did not support forced euthanasia (such as the Nazi use of gas chambers), she strongly supported the movement that led to this. The effects of the eugenics movement can still be seen today; in China, laws such as "Maternal and Infant Health Care Law" have enforced many aspects of eugenics. As a result, the numbers of males is far greater than females because of their "one child" policy and the ability to abort the non-prefered sex.