Iran's parliament has voted to ban permanent forms of contraception, the state news agency IRNA reported, endorsing the Supreme Leader Ayatollah Ali Khamenei's call for measures to increase the population.
The bill, banning vasectomies and similar procedures in women, is parliament's response to a decree Khamenei issued in May calling for more babies to "strengthen national identity" and counter "undesirable aspects of Western lifestyles".
Doctors who violate the ban will be punishable by law, the ISNA news agency reported.
The bill, approved by 143 out of 231 members present in parliament, according to IRNA, also bans the advertising of birth control in a country where condoms had been widely available and family planning considered entirely normal.
The law now goes to the Guardian Council - a panel of theologians and jurists appointed by the Supreme Leader who examine whether legislation complies with Islam.
It aims to reverse Iran's declining population, but reformists see the law as part of a drive by conservatives keep Iran's highly educated female population in traditional roles as wives and mothers.
It also worries health advocates who fear an increase in illegal abortions. State media reported that the number of illegal terminations between March 2012 and March 2013 was 12,000, more than half the total number of abortions that year.
Abortion is legal in Iran if the mother is in danger or if the foetus is diagnosed with certain defects.
During the war with Iraq in the 1980s, Iran offered incentives to encourage families to have more children, but that was reversed in the late 1980s, amid concerns that the rapid population growth could hobble the economy and drain resources.
Khamenei's edict has once again reversed the policy, effectively doing away with the "Fewer Kids, Better Life" motto adopted when contraception was made widely available and subsidized by the state.
Iran's birth rate stands at 1.6 children per woman, lawmaker Ali Motahari said, according to IRNA. At that rate, the population of more than 75 million would fall to 31 million by 2094, and 47 percent of Iranians would be above the age of 60, said Mohamad Saleh Jokar, another lawmaker.
U.N. data suggests Iran's median age will increase from 28 in 2013 to 40 by 2030.
The ministry of health announced in June it would help couples pay for infertility treatment, which can cost between $3,000 to $16,000 in Iran.