In the first decade after the Islamic Revolution of 1979, Iran experienced a baby boom and the population became larger and younger.
But the plummeting fertility rate has reversed that trend. Today, Iran remains a youthful country by Western standards, yet the average age of the populace is starting to creep upwards. Meanwhile, annual population growth, which approached 4 per cent in the 1980s, now hovers around 1 per cent.
Young Iranians, beset by economic crisis, are simply not having children.
Shirin and Hossein are a married couple in their 20s and 30s respectively. They are childless, and so are almost all of their friends.
"Among the couples I know, only one of them has one baby," Shirin said. "To me, the key word for having a child is responsibility. It's a good thing to have a baby, but not now, not in this society, not in Iran. The social and economic conditions are not as they should be."
Shirin's concerns go beyond the struggle to find a livelihood in a country where sanctions, mismanagement and corruption have inflicted terrible damage. There is also the suffocating authoritarianism of a theocratic state.
Pointing towards the TV, tuned to BBC Persian, Shirin said: "Look, we are watching BBC news. But if we had a child at school, the child would not be able to say that we watch the BBC at home." Although satellite dishes are illegal, they are common in Tehran where almost every household has a multitude of channels. The regime is so suspicious of BBC Persian that it tries to jam the station's signal. Nevertheless, millions of Iranians manage to tune in every day.
"We were born as Muslims, but we don't always live as Muslims," explained Shirin. "At school, our child would be pushed into the sort of behaviour [the authorities] want. There is this contradiction in our society. I believe we can have a child when we feel that what we say at home and at school is the same. We can have a child when we don't have to wear a mask on our face."
The authorities are passing new laws to encourage Iranians to procreate. Bill number 446, currently before Parliament, would ban voluntary sterilisation and end all state support for family planning.
Meanwhile, the "Exaltation of Family Bill" would force all state and private sector entities to discriminate against single people in the jobs market. Article nine says the Government and businesses alike should only employ single people "in the absence of qualified married applicants".
Another law already requires couples who want a divorce by consent to first submit to counselling.
Parnian Ghavam, the head of the judiciary's social work and counselling office, is in charge of providing this service. She told the Daily Telegraph that her main aim was to reduce the number of divorces.
"It's obvious that making obstacles to divorce will buy time for the anger and sadness of the couples to disappear and for them to go back to normal life," Ghavam said.
"When you are angry, you suddenly try to make dangerous decisions and divorce is one of them. But when we buy time by making obstacles, then you go back to normal and you love your partner again, especially if there are children."
Ghavam said the state would soon introduce compulsory counselling for couples before they get married. "Is anyone allowed to drive without a driving licence?" she asked. "How are we expecting a good life without proper training courses about married life?"