By Anastasia Moloney

BOGOTA (Thomson Reuters Foundation) - Nearly two in every five pregnancies among girls in El Salvador aged 10 to 12 are the result of rape and incest but the rapists nearly always go unpunished, a U.N. agency has said.

Girls under 12 are four times more likely to get pregnant as a result of rape by stepfathers and relatives, mainly fathers, grandfathers, uncles and cousins, than girls aged 13 to 17, the U.N. Population Fund (UNFPA) said in a report this week.

Under Salvadoran law, having sex with a child under 15 is a crime that is regarded as rape, which carries a jail sentence.

But of the 1,445 reported cases of girls aged 10 to 14 who got pregnant last year, there were no convictions against perpetrators of the crime.

"None of them have been prosecuted by the institutions that have to do that," said Hugo Gonzalez, UNFPA's representative in El Salvador.

He said one of the reasons why few perpetrators are punished is because families are reluctant to report the crime and because some poor families see pregnant daughters as a financial burden and push them into marriage with their rapists.

"Families on the one hand are confronting teen pregnancy by somehow pushing girls to get married even with the ones who perpetrated the rape..," Gonzalez told the Thomson Reuters Foundation in a telephone interview.

"On the other hand if the male who made the girl pregnant is a relative of the girl, the family doesn't open a case to protect the honor of the family instead of protecting the rights of the girl," he said.

On top of suffering sexual abuse, girls who become pregnant cannot have a legal abortion, which is banned without exception in the socially conservative nation.

Last month, El Salvador's ruling leftist party presented a bill to Congress to allow abortion in cases of rape or risky pregnancy, offering a glimmer of hope to girls and women who do not want to go through an unwanted pregnancy.

A third of all births in the Central American nation are to teenage mothers, one of the highest rates of teen pregnancy in Latin America.

The study, which surveyed 424 girls who gave birth in 2012, reported that one in four girls said their first sexual experience "wasn't consensual."

In most cases, girls said they were persuaded to have sex because their boyfriends told them it proved that they cared for them, and that there was no risk of getting pregnant when having sex for the first time.

The study also found girls who dropped out of school were far more likely to get pregnant, with 80 percent of girls saying they left school before becoming a mother, especially those from poor families living in rural areas.

CHILD MARRIAGE

According to the study, teen pregnancy is both a cause and a consequence of child marriage, depending on the girl's age.

Child marriage puts girls at greater risk of domestic and sexual violence and keeps them in poverty, the study said.

In El Salvador, a girl can get married under 18 with a parent's permission if they are pregnant or have a child.

"The study found that girls aged 15 to 17 get married first and then get pregnant, but in the case of young girls, 10 to 12, they get pregnant first and then get married," Gonzalez said.

He said improving access to contraception, ensuring more boys and girls use birth control methods, and better sex education in schools are key ways to tackle teen pregnancy.

(Reporting by Anastasia Moloney, editing by Ros Russell.; Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, corruption and climate change. Visit http://news.trust.org)