Huyen, 29 years old and 14 weeks pregnant, waited nervously at a Hanoi maternity clinic.
With two young daughters at home and two abortions behind her, she was hoping to hear staff look at the sonogram and say, "Looks like the father!"
In Vietnam, such code phrases are used to get around laws proscribing medical staff from disclosing gender while the foetus is young enough to abort without medical grounds.
Ms Huyen was hoping for a boy, in line with the country's patriarchal traditions; another girl would bring pressure from her husband and in-laws for a third abortion.
Gender-selective abortion is illegal but on the rise in Vietnam, and contributes to the country's highest abortion rate in the region, according the UN Population Fund.
The lack of stigma, and increased teenage sexual activity, have driven up abortion rates, which have reached one termination for every five live births per year, according to the Health Ministry.
Abortions by choice are legal up to 22 weeks of pregnancy, and typically cost about $150 (5,300 baht).
A recent proposal by the Health Ministry to lower the limit to 12 weeks, except in cases of rape or medical problems, has been met with widespread public criticism.
Within the high abortion rates, gender-selective terminations are a distinct problem, despite 12 years of laws and initiatives against the practice.
In 2014, a record of 112.4 boys were born for every 100 girls, up from 106 boys in 2003. In 16 localities, the male ratio exceeded 115, topping out at 124.4 at northern province of Quang Ninh.
At that rate, Vietnam would have 4.5 million more males than females by 2050, some studies say.
"Vietnam will face the problems China has faced because our sons will have trouble finding wives," said Khuat Thu Hong, director of the Hanoi-based Institute for Social Development Studies. China saw nearly 118 boys born for every 100 girls in 2011.
"Vietnam will face more social problems such as prostitution and women trafficking."
Some women say that their husbands blame and beat them if they don't produce sons, even though gender is determined by the father's chromosomes.
Machismo is a key factor, said Pham Thu Hien, a gender-bias expert with UN Population Fund who worked several years as a gynaecologist and obstetrician.
"Some men feel like they are not real men if they don't have sons," she said.
Gender imbalance among newborns is increasing in Vietnam, China, India and several other smaller countries, as newly prosperous populations use modern technology to obtain the traditionally favoured male children.
So each year, thousands of Vietnamese women told by medical staff they are carrying a "butterfly" rather than a "bird" -- another code -- will opt for abortion, often with a gender-neutral explanation.
"They'll say, 'We're too poor -- we can't afford it' or 'The time isn't right'," said Ms Hien, herself a mother of two girls, aged 20 and 16. "They don't tell the truth because they know it is wrong."
There is no ignorance of the law, Ms Hien said.
During field research in a remote province, clinics were posted with signs informing clients of laws prohibiting the discussion of gender, and doctors and nurses insisted they strictly observed the laws, she said.
Village women seldom said they had aborted because of gender, but all said they new someone who had, usually citing pressure from husbands and in-laws, she said.
Confucian tradition values sons to manage family wealth, care for ageing parents and perform rituals to honour ancestors.
Couples also use a range of measures to increase the chance of conceiving male children. Some women try to determine the moment of ovulation or their variations in body temperature in the belief that precise timing of conception can influence the baby's gender, Ms Hien said.
More affluent couples use more scientific methods, including going abroad.
Ms Hien said she knows of one couple with two daughters who travelled to Singapore for in vitro fertilisation that produced twin sons.
The government has tried several measures to ease pressures on families and hopefully reduce the impact of gender preference.
A previous two-child limit applied to government workers was lifted, and there are proposals to offer families extra insurance or tuition for girls.
A UN-backed awareness-raising campaign has run under the slogan "Being a Girl Is Cool".
Ms Huyen emerged from her appointment with a glum expression.
"Another butterfly," she said. "My husband will be unhappy."
The doctor had warned her that a third abortion, and in her 14th week, could have health implications.
"But I would rather suffer from health problems than have the third girl," she said.