In a report released on Tuesday, Amnesty International said capital punishment in the west African country curbs women's rights to a fair trial and exposes them to homicide charges for abortion-related offences.
The organisation said Nigerian women "of socio-economically deprived backgrounds, who are illiterate, have no husband and become pregnant are disproportionately affected" by the country's laws.
The death penalty is enshrined in Nigeria's constitution and in Islamic law in 12 northern states for a range of crimes including armed robbery, treason, murder, and culpable homicide.
There have been "at least 33 death sentences since 1999", a summary of the report said.
It added: "One of the convicted was a woman charged with a capital offence of culpable homicide, after allegedly having had a still-born baby, which event the court termed as an illegal abortion."
"By using the death penalty to regulate sexual behaviour, other rights are also being violated, such as the right to be free from discrimination, freedom of expression and association and the right to privacy," said Amnesty, which is fiercely against the death penalty."
As of July last year, there were 487 people on death row, 11 of whom were women.
Amnesty said some women detained on serious offences had been kept in prison for up to 10 years while awaiting trial.
"This in itself amounts to cruel, inhuman and degrading treatment according to international human rights law," the London-based group said.
The report criticised Nigeria's version of Islamic law, or Sharia, in particular for its punishment of Muslims found to have engaged in extra-marital sex - 100 lashes for unmarried individuals and death for unfaithful spouses.
"By using the death penalty to regulate sexual behaviour, other rights are also being violated, such as the right to be free from discrimination, freedom of expression and association and the right to privacy," said Amnesty, which is fiercely against the death penalty.
"The organisation opposes the criminalisation of consensual sexual relations between people over the age of consent," it said.
And Amnesty called on a Nigerian parliamentary group studying capital punishment to recommend the government "follows the international trend in abolishing the death penalty for all crimes for once and for all".
The use of the death penalty in Nigeria gained international attention last year after single mother Amina Lawal was sentenced to death by stoning for adultery. She was later acquitted of the offence.
Ibrahim Zakzaky, the influential leader of the Nigerian Muslim Brothers, has said the nature of Sharia in Nigeria overemphasises its penal aspects, thus making a mockery of Islam.
Abuse of Islam
And Masud Shadjareh, of the London-based Islamic Human Rights Commission, told Aljazeera.net after the Lawal acquittal the death penalty had a major role to play in shaping an equitable society.
He said: "There is so much corruption in Nigeria and I think Sharia is just being used as a stick to beat the poor while the rich still lead a life of luxury."
He added: "But the implementation of Sharia in an Islamic environment and when the conditions are right is a different thing. The real implementation of Sharia is not barbaric - it leads to a just society.”