Alioune Tine, Amnesty International's regional director for west and central Africa, described the ban as being "misguided", saying that it would not be able to solve the West African country's teenage pregnancy debacle.
"The prohibition on visibly pregnant girls attending mainstream schools and taking exams is hopelessly misguided, and is doing nothing to address the root causes of Sierra Leone's high teenage pregnancy rate, which surged during the devastating Ebola crisis, and remains high despite this ban," said Tine.
Tine called on the country's authorities to increase sexual education which he said would help improve the already dire situation.
Highest teenage pregnancy rates
In a 2015 report, the group said at least 10, 000 girls were affected by the ban.
Reports indicated that there was an increase in teenage pregnancy during the Ebola outbreak.
A study in 2016 by the Secure Livelihoods Consortium said that UNFPA surveys indicated that at least 18,119 teenage girls became pregnant during the Ebola outbreak.
Even before Ebola broke out in late 2013, Sierra Leone had one of the highest teenage pregnancy rates in the world, with 28% of girls aged 15-19 years pregnant or having already given birth at least once.
The Committee on the Rights of the Child in its recent review in October 2016 urged Sierra Leone to immediately lift the discriminatory ban on pregnant girls who were attending mainstream school and sitting exams.
It further said that the country should ensure that the pregnant girls and adolescent mothers are supported and assisted in continuing their education in mainstream schools.