The World Health Organisation carried out a study to find if women in 35 low and middle-income countries use modern methods of contraception.
The results stated that 15 million out of 16.7 million unwanted pregnancies a year could be avoided.
Researchers carried out an analysis of the demographic and health surveys of 35 countries, conducted between 2005 and 2012. Of the 111,301 non-pregnant women who did not desire pregnancy, Ghana contributed the smallest number, 0.4%, and India the largest, at 17.1%.
A statement by the European Society of Human Reproduction and Embryology said, "Out of 12,874 women with undesired pregnancies covered by the study, India contributed the largest number."
70.8% non-pregnant sexually active women who did not want any future pregnancy used contraception, 15.7% women did not use any form of contraception, but expressed the desire to do so and 13.5% did not desire to use contraception.
Universal access to reproductive health was one of the millennium development goals agreed by the United Nations in 2005, but authors of the study said of all the health-related MDGs, universal access to reproductive health is the one that is most off-track.
Modern methods include combined oral contraceptives, male and female condoms, progestogen-only pills, implants, injectable contraceptives, intrauterine devices and sterilisation.
"Health concerns were the most common reason given for not using modern contraception, yet these concerns are not backed up by evidence," said Howard Sobel, regional coordinator of the reproductive, maternal, newborn, child and adolescent division at WHO, western Pacific regional office, and one of the co-authors of the study.