Sebastian Berger, Dili – Her belly swollen with her seventh child, Fernanda Sarmento paced the corridors of Dili's National Hospital as she waited to give birth.

"It's good if I have a lot of children," said the 38-year-old, adding that she wanted another girl to add to her two existing daughters.

Seven children may appear a large family but in East Timor, which has the highest fertility rate in Asia and is among the world's top five, it is entirely average.

Birth rates have increased dramatically since it broke away from Indonesia in 1999, with many Timorese believing they need to replace the 200,000-plus who died in the years following the invasion.

A perception that the occupying Indonesians wanted to breed them out of existence – family planning was actively promoted during the occupation – adds to the incentive. Anecdotes abound of women who lost, for example, eight out of 12 siblings, having nine children themselves.

Flicking through the admissions book on the maternity ward shows several women with 'previous pregnancies' in double figures. "12 is normal," said Florentina Corbafo, the senior midwife. The highest she has seen is 15. "It all depends on the mothers, they want more and more and more."

According to UNFPA, the United Nations Population Fund, using census data from 1999 to 2004 average lifetime fertility in East Timor is 6.95 children per woman.

Nowhere in Asia comes close – in neighbouring Indonesia the figure is 2.4 and in Singapore it is a mere 1.06. Only a few countries in Africa such as Nigeria and Mali surpass it, and one survey put the Timorese statistic at 7.77, which could put the nation's women at the top of the world's breeding table.

But the trend is pushing an already fragile country deeper into trouble, said Hernando Agudelo, the UNFPA country representative in Dili, adding that the idea of replacing those killed was misguided.

"People don't understand the linkages between population and development. It's not because you have more people that you are going to have more wealth. What you are making grow is the poorest of the poor."

There are demographic factors in its continuing crisis, with many young people undereducated and unemployed, Dr Agudelo said, and at current rates the population will double in 17 years, leaving the country stuck in poverty despite the oil wealth piling up in accounts in New York.

"You can't grow the number of schools, the quantity of water or electricity or food in the same manner," he pointed out.

At the hospital Mrs Sarmento, whose husband is a subsistence farmer, was having none of it. "In the future they can look after us," she said of her brood.