The legality of and public opinion toward abortion in Norway has changed dramatically in the last 100 years. Current Norwegian legislation and public health policy provides for abortion on demand in the first 12 weeks of gestation, by application up to the 18th week, and thereafter only under special circumstances until the fetus is viable, which is presumed at 21 weeks and 6 days.
In Christian V's legislation of 1687, abortion was punishable by death. By law of 1842, it was no longer a capital offense, but could be punished by up to six years of imprisonment and hard labor. In 1902, new legislation allowed for abortion in cases where the mother's life was in danger or the child would be stillborn.
An important milestone for the issue of abortion on demand came on January 15, 1915, when Katti Anker Møller gave a speech in Kristiania calling for legalized abortion on demand. She said that "the basis for all freedom is the governance over one's own body and everything that is in it. The opposite is the condition of a slave." ("Grundlaget for al frihet er rådighet over egen krop og hvad i den er. Det motsatte er en slaves tilstand")
In the period between 1920 and 1929, about 100 individuals were sentenced for illegal abortion. In one of Oslo's largest hospitals, 82 women died as a result of illegal abortions, and 3791 women were treated for injuries sustained under these procedures.
In 1934, the ministry of Justice named a committee to start work on new legislation on abortion, headed by Katti Anker Møller's daughter Tove Mohr. The following year, a campaign opposing the committee's work gathered 207,000 signatures. The government tabled the committee's work.
The political debate continued on the issue, though World War II put other priorities in the public discourse. During the German occupation, the maternal hygiene offices pioneered by Katti Anker Møller were shut down and all their materials put to the fire.
When the maternal hygiene offices reopened in 1950, abortion counseling became one of their main services. An estimated 3,000 legal abortions and 7,000 - 10,000 illegal abortions were performed each year in the 1950s. In 1956, the prevalence of illegal abortions reached such levels that a council on penal law recommended stiffer penalties for illegal abortions.
In 1960, a new law allowed abortion by application approved by a commission of two physicians, and only on the basis of medical, eugenic, or criminal criteria; and with the consent of the husband if the applicant was married. This law went into effect in 1964.
The application was made by the woman's physician on her behalf, and she made her case alone before the commission. In 1964, 72% of the applications were approved. By 1974, 94% were approved, and the rate increased steadily through the 1970s. Still, practice varied considerably.
In 1969, the Norwegian Labour Party put abortion on demand on their platform, setting the stage for a mainstream debate on abortion within the broader framework of feminism. Proponents of abortion on demand improved their organizational strength, forming in 1974 Kvinneaksjonen for selvbestemt abort ("The Women's campaign for abortion on demand"). At the same time Folkeaksjonen mot selvbestemt abort (the Popular Movement Against Abortion on Demand) was formed and led by Anne Enger Lahnstein, submitting 610,000 signatures for their cause. The debate intensified, with feminists on one side of the issue, mainstream Christians on the other, and the medical community split.
Abortion on demand was put to the vote in Stortinget but unexpectedly failed to pass by one vote when Socialist Left party representative Otto Hauglin voted against the bill. Although criteria for commission-approved abortions were somewhat relaxed, it became clear that abortion on demand would have to wait for the next session of parliament.
This period marked intensifying activism on both sides of the issue. The Christian newspaper Vårt Land became the platform for those opposed to the pending legislation, whereas the Socialist and feminist press advocated for it. The non-Socialist parties were unified in their opposition to abortion on demand, maintaining that the commission arrangement was appropriate.
In 1978, after much preparation and activism, by among others physicians Berthold Grünfeld and Axel Strøm of the Norwegian Labour Party and Socialist Left Party, respectively, passed with a one-vote majority the current law, which provides for: abortion on demand in the first 12 weeks, between the 13th and 18th week abortion by commission approval on medical, eugenic, criminal, humanitarian, or social reasons. After the 13th week of gestation, abortion is in principle outlawed except under exceptional circumstances. Soon after, bishop Per Lønning resigned from his office in the Church of Norway in protest against the new legislation.
Although some argued that easier access to abortion would cause abortion rates to increase, the number of abortions has remained stable since the early 1970s, especially when adjusted for demographic changes related to fertility.
Between 1999 and 2003, 1740 applications for abortions between the 12th and 16th week were considered by commissions in Norway. Of these, 1647, or 95.2% were approved 
In 2011, midwives at Rikshospitalet alarmed authorities that some aborted fetuses had heartbeats for up to one hour before they died. Data from the Norwegian Institute of Public Health revealed that between 2001 and 2011 17 fetuses had been aborted at 22 or 23 weeks gestation. In September 2013, a committee appointed by the Ministry of Health and Care Services recommended that abortion should not be allowed after 21 weeks and 6 days gestation. On 1 January 2015 the regulation on abortion was changed to say that a fetus is presumed viable at 21 weeks and 6 days, unless there is specific reasons to believe it is not.
As of 2010, the abortion rate was 16.2 abortions per 1000 women aged 15–44 years.