Mother and child were discovered in Pulkwa, located in the Borno state, according to the Nigerian military.
Cameroon part of regional force against Nigeria-based Boko Haram, which also attacks neighbouring countries.
Women told HRW they were drugged and raped or coereced into sex through false marriage promises.
Eyewitnesses told local media the blasts took place near a camp for displaced people in Maiduguri.
In 2015, a faction of Somalia-based al-Shabaab terrorists pledged alliance to the Islamic State terror group
Soldiers went missing during heavy fighting in Gashigar village, on the border with Niger, on 17 October.
Women are not a commodity to be won and lost in war.
President vows government will fight to ensure remaining 197 girls kidnapped in Chibok will be released.
IBTimesUK interviews researcher Atta Barkindo, who has translated several Boko Haram videos and audio clips.
The attack came amid speculation that many abducted Chibok girls are unwilling to leave their captors.
Days after the release of 21 of the 219 girls kidnapped by Boko Haram in April 2014 others may be freed.
Situation at the maximum security centre is unclear but Niger has often been attacked by members of the terror groups.
The kidnappers were said to be taking the hostage across the border to Mali.
The Nigerian president hopes to get enough intelligence from the released girls to secure freedom for the rest.
EXCLUSIVE Swiss government tells IBTimes UK about its role in negotiations with Boko Haram.
Chibok abduction not the first Boko Haram mass-kidnapping, but only one to attract international outrage.
Chibok mass-kidnapping in 2014 shone a spotlight on deadly insurgency of Boko Haram in Lake Chad region.
Borno state is epicentre of Boko Haram's insurgency, which has claimed at least 20,000 lives since 2009.
Niger's Prime Minister Brigi Rafini said in a television address that the death toll could rise.
Report says Boko Haram changed recruitment strategy following increase of security in militant-held areas.
Barrister Wakil speaks on ways to end insurgency as Boko Haram 'asks her' to represent them in peace talks.
The operation was launched in July after a surprise attack by the militants killed 30 Niger troops in June.