When Shin Dong-jin first started turning up in South Korean country villages in 1968 at the age of 22, he wasn't always made to feel terribly welcome. He was not an unruly young man. At one time, he had ambitions to be an accountant. But instead he became an educator with the Korean Planned Parenthood Federation, and the reason he went to the villages was to tell farmers' wives not to have any more babies.
"It was weird from their point of view," says Shin, sitting in his Seoul office, where the walls are covered in family planning posters. "This green, single guy who still smells of his mother's teats would come up to them and talk about family planning. It was like trying to write in front of Confucius.
"Talking about sex at that time was extremely taboo. To even look at a woman's calf was extremely arousing - when [singer] Yoon Bok- hee wore a miniskirt the whole of Seoul flipped."
It wasn't just the women who had their doubts; their husbands were also suspicious. Shin often found himself sitting around a lantern drawing pictures for a group of women to explain how contraception worked. Occasionally the men of the village, curious about the tall young stranger, would peep through the paper doors and see him holding up graphic pictures to their wives. "All hell would break loose," says Shin, who is now 60. "The village leader would try to convince them that it was all right, but sometimes I had to flee from the village in the middle of the night."
Shin persevered with his job, in part because he was "completely mesmerised" by the over-population problem then facing Korea's 30 million mostly rural people. The birth rate - the average number of children per woman - was 4.53 and it was Shin's job to explain the economic damage this was likely to have on Korea, then one of the world's poorest nations.
"Daughter or son, stop at two and bring them up well," said the posters he used to hand out. And that is exactly what people did. So much so that today Shin is still working at the planned parenthood federation, but instead of trying to persuade people to stop reproducing, he is desperately trying to get them to start.
In the 38 years he has been at the federation, Korea's birth rate has plummeted to just 1.08 - the lowest in the developed world. The economic think-tank, the Korea Development Institute, estimates that the country's economy will start slowing by 2010 unless the birth rate begins to rise. The situation has become so grave that the median age of the Korean population is forecast to rise from 31.8 years in 2000 to 50.9 by 2040, which means that more than half the population will be over 50 within a generation, and there won't be enough younger people to support them.
So these days Shin is in charge of encouraging Koreans to have more babies. His latest leaflets say: "Get pregnant within a year of marriage and have two children by 35." This complete U-turn underlines the astonishing pace at which Korea has developed. When Shin started working, it was an agrarian nation where 75 per cent of the population lived on farms and children were considered a source of both labour and wealth. At that time, the average annual income was $250 and official figures forecast that each percentage point increase in the population would slow economic growth by 3 percentage points. Park Chung-hee, the authoritarian president who masterminded Korea's economic development during the 1960s and 1970s, set about trying to lower the birth rate.
But his policies, which made it economically disadvantageous to have more than three children, coincided catastrophically with Korea's rapid industrialisation. When companies such as Samsung, Hyundai and Daewoo started hiring for factories, Koreans increasingly abandoned their farms and moved to the cities, where they didn't need children to help in the fields and didn't have as much space to house a big family. The average income grew to $16,300 and Korea is now the world's 10th biggest economy, renowned for making cutting-edge mobile phones and specialised shipbuilding.
All this was unimaginable to the young Shin when he first joined the planned parenthood federation in the late 1960s. "It was April 1968," he says. "I thought, wow, this is really a big international problem, and in Korea the problem was even bigger. So it was a really important issue and if I was going to do something good for our society, then family planning was really something worth dedicating my life to."
After a brisk two-week training course he was dispatched to the villages. The villagers may have been shocked to hear Shin's frank reproduction advice, but he was comfortable with the subject. "At high school I studied stockbreeding," he says. "It wasn't people, but sexual reproduction issues were familiar so the job was quite apt for me."
He began by forming "mothers classes" of 20 or so wives in each village. "We just talked about life, like the flood last year, how difficult it is to make a living... how we are short of rice, how good it would be if we had a good harvest," says Shin. Many families said they were having a hard time, that they were "living because we can't die".
"Then I'd say that a good harvest was not the only way out - we could instead reduce consumption. In Korea there is an old saying: 'Instead of trying to cultivate the paddy field right in front of our gate, it would be better to reduce the number of mouths.'"
The women would often tell him that having children was "up to the skies", whereupon Shin would open his bag full of condoms, contraceptive pills and vasectomy information. Explaining the nitty gritty to even the willing listeners was not always easy. The villagers often had strong Shamanistic traditions and superstitious beliefs.
"When we talked about condoms, we would show how to use them on a stick," says Shin, grabbing the golf club from the corner of his office to demonstrate. "But one day I went to a village and there were these condoms hanging on the fence posts. So I asked why they were there. The woman replied that after they had finished doing 'what married people do', they had put the condoms on the sticks as contraception.
"At that time, people were very spiritual so they thought it was some kind of Buddhist good fortune tag or something. I couldn't even laugh," he says, laughing uproariously now.
At other times, husbands would complain to Shin that their wives had still become pregnant even though the men had been conscientiously taking the pill every day.
Shin was certainly a true believer. In 1979, when he was 33, his wife gave birth to their daughter, Jung-a. "I was crazy about family planning - you could say that my face was a family planning advertisement - so about three months later I told my wife that one daughter was quite enough and I was having a vasectomy," he says. "The next day I went to work and suddenly my mother popped in for a visit in the office. She grabbed hold of my tie and shouted 'you're going to have a vasectomy? Let us both die then!'"
The next day he was summoned to see his father-in-law. "It's just not right!" the older man shouted, as Shin knelt before him on the floor for more than an hour.
"Eventually, because my knees hurt so badly, I had to give in and agree to have more children," he says. Two years later they had a son.
In the rest of Korea, Shin and his family- planning colleagues were having great success. By the 1980s, the birth rate had dropped to 2.83 and the government announced it wanted it to fall to 2.1 by 1990.
To help speed the process, those who agreed to have a contraceptive operation received a Won100,000 ($165 at the time) payment and priority to buy apartments. Parents who had more than three children lost government refunds for money spent on their children's education. Men could even trade some of their army reserve training days for time off to have a free vasectomy. By 1988, to Shin's disbelief, the ministry of statistics declared that the target had been achieved. But he was too successful. What appeared to be a gentle reduction in the number of births turned out to be steep, exacerbated by migration into the crowded cities, women's greater participation in the workforce and rapidly increasing living costs.
In keeping with those changes, Koreans started placing more emphasis on education, much of which was done at expensive private cram schools. A decade ago, the average Korean family spent Won183,000 - about 8 per cent of average household income - on private education for each child per month. Now it spends Won310,000 - 14 per cent - a month.
By 1990, the birth rate had fallen to 1.59, creating the fastest ageing society in the world, and Shin's job description was rewritten. "Before, I was working to restrain population growth. Now it is completely the opposite," he says. "I focus on pro- marriage education programmes for teenagers, also pro-birth programmes, and then supporting married couples that are infertile."
But again, Shin's own family is evidence of the struggle he faces. His daughter Jung-a, now 28, is in no hurry to contribute to population growth, much to her father's disappointment. "My job title is the director of the low population department, so I establish pro-marriage programmes and I tell young married couples to have children quickly. But I can't even convince my own daughter to get married," he says, taking out his key ring which has a photo of his daughter on it that he shows to potential sons-in-law.
"She herself has doubts about whether marriage is really necessary... so I feel like dying," he says, adding with relief that his son "is up for marrying" once his income is more stable.
To counter women's increasing participation in the workforce and concerns about the cost of schooling, the government introduced a range of measures such as 90 days' guaranteed paid maternity leave.
Meanwhile, the federation recently started a more emotional campaign to encourage Koreans to have more babies.
"It doesn't work if you just say 'Let's have babies!'" says Shin. "We're showing lots of images of people happy because they have a baby and the preciousness of children and family, to touch their emotions."
The government is now making aggressive efforts to encourage more births. It announced last month it would spend more than Won30,000bn over the next five years to try to raise the birth rate. About 80 per cent of families with children under the age of five are due to receive childcare allowances. The number of nursery schools will be doubled and state schools will receive funding to run their own after-school classes.
The private sector is joining the effort. The Korea Stock Exchange, for example, gives employees a Won5m bonus when they have a third child.
Shin is optimistic that he and his colleagues will be able to convince Koreans to have more babies, just as they persuaded them to have fewer in the 1980s. They are looking to France, which he says has been the most successful at boosting its birthrate.
"They created an environment conducive to having children through education and welfare policies," says Shin. "Also, their policy was implemented over a long time so there was no immediate financial burden," he says.
One cause for optimism is that the expected number of births in Korea is relatively high. A survey by the Korean Women's Research Institute last year found that the average number of children that Koreans want is 2.2.
"So, people are getting married late and even when they do, they're not having enough babies but that doesn't mean I'm pessimistic about the future. I still have hope," he says. "Why? Because of Korean culture - this is a culture where one's family and family name is important. The second reason is that when we say 'let's do something', we'll do it. Look at our family planning policy in the past, the speed at which it was achieved was unprecedented."
Then he puts his key ring back in his pocket and mutters, "If only I could convince my daughter to get married."