The strategy of intervention in Tanzania to reduce total fertility rate must address rural women who are the poorest.

Religious leaders are very powerful in shaping people’s attitudes that could help reduce rapid population growth in many parts of Tanzania, a country with a large population of young people under 18 years.

In many parts of Tanzania Mainland and Zanzibar, there are lessons taking place on the issues of sex, contraception, HIV and AIDS under the Tanzania Interfaith Partnership (TIP).

The TIP partners include Christian Council of Tanzania (CCT), the National Muslim Council of Tanzania (BAKWATA), the office of Chief Mufti of Zanzibar and the Tanzania Episcopal Conference (TEC).

These partners have a vast community network from the national to grassroots level.

The grouping of religious scholars and medical professionals team up with the aim of shifting deep-rooted views in Tanzania Mainland and Zanzibar, where Christian and Islamic societies dominate and regard contraception as a sin against God.

"Although the Qur'an is 1,400 years old, it is still alive," says Zuberi Muhidin, Secretary of both the Zanzibar Imams Association and the Zanzibar Interfaith Association for Development and AIDS, (ZIADA). "The verses can be interpreted for today."

The Secretary of ZIADA and Imams Association, Muhidin reads from the new book Ziada has produced to examine whether family planning can be considered against Islamic belief.

"In Chapter Two, verse 233, for example, it says: 'The woman giving birth should breastfeed for two years'," he says. Muhidin argues that the ontraceptive effect of breastfeeding means the verse demands a spacing of almost three years between births, signifying that the spacing of children is endorsed by the Qur'an.

Zanzibar's population is growing at more than 3 per cent a year. Compared with the Tanzanian mainland, Zanzibar has half the rate of use of contraception – just 13 per cent in fertile women according to figures obtained in 2011. The island has more than double the proportion of Muslims, at 95 per cent than Christians or other denominations.

While tackling these controversial issues is fundamentally about the right of women to plan their families, the probable knock-on effect of curbing Zanzibar's rapid population growth is also vital, says Felister Mayala Bwana, National Programme Officer for Reproductive Health for the UN Population Fund in Tanzania. The fund gives support to Ziada.

"Even the existing 1.2 million people are too many for Zanzibar to sustain," says Bwana, without a transformation of the economy and infrastructure that is not happening.

[[The population is growing more than 3 per cent a year, with each woman having more than five children on average, and the population density on the dry island is 400 per square km.

Increasing access to contraception is at the heart of one of the UN's millennium development goals (MDG5), improving maternal health. One of the MDG5 targets is a 60 per cent rate of contraceptive use by 2015. "That is very, very challenging," says Bwana, but can be achieved at a price.

For the 45 million people on the Tanzanian mainland, there is a plan to meet the goal, costing 133bn Tanzanian shillings. According to National Family Planning Costed Implementation Plan (NFPCIP 2010)

However, the work done by Muhidin and his colleagues is starting to have an impact: contraceptive use has increased from 9 to 13 per cent in the past four years.

"Religious leaders are very influential here," says Hamid Nasser, a member of the Zanzibar AIDS Commission and Co-ordinator of the Zanzibar Faith-Based Organisations group, which works with Ziada. "The people follow the Qur'an, but the interpretation has to link to modern ways." Condom use, he argues, is a modern equivalent of the traditional withdrawal method. He says that while it used to be the husband's decision when to have a child, religious leaders now teach that the Qur'an says both partners decide together.

"But," says Nasser, banging the table for emphasis, "there are conditions." Modern family planning methods are only acceptable if they are prescribed by a qualified Islamic Doctor, he says, and aimed at protecting the mother's health. In Zanzibar, the scholars' council that sits above the imams issued a fatwa condoning condom use under these conditions.

Furthermore, Nasser says, condoms must only be prescribed from hospitals, not be handed out for free: "Children will take them and they will go everywhere." Muhidin says that nor is the idea of "controlling" population acceptable: "Even when times are hard and life is a struggle, God is the one who gives."

To make more progress, says Muhidin, more efforts will be needed to cover other methods of birth control. While the individual imams are agreed, the scholars' council "takes decisions for the entire population", he says, and so deliberates slowly. Ziada's work on tackling these cultural issues is vital, says Julitta Onabanjo, the UNFPA's head in Tanzania.

She says: "It is not just an issue of getting contraceptive commodities to people, you have to be sure they want to use them, and are able to use them when they want to, whether to plan children, space them out or not have children at all."

But contraceptives supply in Tanzania is another issue. Data show that contraceptives use in the last 20 years has tripled from 10 per cent in 1991 to 34 per cent in 2010. But twice as much use of family planning methods is for women in urban areas compared to those in rural areas.

The rural fertile rate is 6.1 compared to that of urban which is 3.7, which means it is the rural population that drives fertility in Tanzania. Therefore, the strategy intervention in Tanzania to reduce total fertility rate must address rural women who are the poorest.