For rural areas, post-partum insusceptibility reduction is slightly higher (0.7 months). On the contrary, there is an increase in insusceptibility for urban areas from 5.6 to 7.5 months between 1997 and 2002. Overall, the median duration of post-partum insusceptibility in rural areas is higher than in urban areas. The observed decline in the duration of post-partum insusceptibility tends to increase in the marital fertility rate, which might have been offset by other inhibiting factors, such as an increase in contraceptive use.