what could be the reasons for such variations?

India's literacy level is very low. People don't have proper education and discriminate between male and female children. In states like Kerala there are well educated people who also follow matriarchal society rules and sex ratio in Kerala is 1058 females per 1000 males. Indian society is male dominant society. The people here have remained in favour of male child leading to female foeticide and dowry problems which makes people think of female children as a burden. Many rural areas of India are having proper medical facilities.