For better population indicators, region and religion both matter, suggest data from 2011 and 2001 decadal Censuses.

According to the data, in the more developed southern States all communities do better than in the more backward northern States.

Poor education indicators

Between 2001 and 2011, Muslims (24.65 per cent) remained the group with the fastest population growth, followed closely by Scheduled Tribes (23.66 per cent) and Scheduled Castes (20.85 per cent). All three groups have historically had poor education indicators, especially for women, and restricted access to health care.

However, in States such as Kerala and Tamil Nadu, which are considered advanced in terms of income and development indicators, population growth is low for all communities, the numbers show.

The population growth rate for Muslims in Kerala, for example, while substantially higher than that for Hindus or Christians in the State, is lower than the national average for Hindus, and half that of Hindus in States like Bihar.

“When the demographic transition is occurring, the better off communities first reduce their fertility, which is then followed by poorer communities. This is exactly what we are seeing, and in developed States, access to education and health becomes available to all,” Dr. P Arokiasamy, demographer and professor at the International Institute for Population Sciences, Mumbai, said.

A similar trend is observed in other States; those with higher than average Hindu growth rates have higher than average Muslim growth rates too.

Two notable exceptions are Assam and Uttarakhand, where the Muslim growth rate is significantly higher than the national average, while the Hindu growth rate is lower.

“It is undeniable that in the border districts of Assam, there is illegal immigration. There is no other explanation for the Muslim population growth there,” a senior Census official said.

Worst sex ratio

When it comes to sex ratio, Sikhs as a community had the worst sex ratio in 2011 at 903 females for every 1,000 males, followed by non-SC/ ST Hindus (929), while Christians had the best sex ratio (1,023 females for every 1,000 males) followed by STs (990). Here again, region matters.

In Punjab and Haryana, all communities see their sex ratios plummet to their worst, while in Kerala, the sex ratio of all communities except Sikhs and Buddhists rises above 1,000 females for every 1,000 males.

In Tamil Nadu, the sex ratio for Muslims, Christians and SCs rises above 1,000.