Declining Proportion of Girls at Birth at Cuddalore District, Tamil Nadu, India, 2001 to 2011 - Cause for Concern

Objectives Cuddalore District of Tamil Nadu, India showed decline in sex ratio of children less than six years from 957 girls per 1000 boys (census 2001) to 895 (2011). Study objectives were to identify contributing vital statistics, describing its time, place distribution and to generate hypothesis regarding etiology. Methods We analyzed trend of female live birth proportion for total births and each birth order. We calculated ratio of female to male rates of infant, child mortalities and still birth. We mapped birth sex ratio of blocks from 2007 to 2011 and that of each birth order for 2011. We compared actual number of female and male live births with expected number for each birth order every year. Results Female live birth proportion showed declining trend (P valueless than0.001). Female to male ratio of infant, child mortality rate and still birth rate were within normal range. Among 13 blocks, number of blocks with birth sex ratio more than 950 decreased from five to zero, from 2007 to 2011. During 2011, only four, one and zero blocks had ratio more than 950 for first order, 2nd order and higher order births respectively. Second and higher order births had significant declining trend for female proportion (P values less than0.001). Though first order births had no significant trend, it showed less female live births in comparison to expected number during some years. Conclusion Low child sex ratio was due to low birth sex ratio. Decline had spread to more geographical areas with time. Higher order births were more affected suggesting female sex selective abortion as hypothesis. Block as monitoring unit and monitoring of higher order pregnancies were recommended.