She is not a clown, although some days it feels that way, but a “baby wrangler”. The job involves coaxing smiles or tears from infants on photo and film shoots for advertisers and for editorial.

Physically and mentally draining is how the relentlessly upbeat 48-year-old describes the job. It helps that she is an ex-dancer, surfer, swimmer and yogi. “I'm on my feet all day, running, jumping, dancing and falling on my butt to make the kids laugh and [my sporting hobbies] also give me the mental strength to be patient.” She finds parallels between surfing and wrangling: “The smallest wave can give you your best ride if you know how to enjoy it. The shyest or wildest kid can give you your best shot if you have the patience.” Imitating a duck's quack or a monkey's babble can help.

While she loves children she never wanted to have any herself. “I get the best part of kids – they look nice and they smile. Then they go home. Mums say to me: ‘How do you have the patience to get my kid to do that?' I say: ‘It's because it's not my kid'.”

As the market for infant products grows, a heavy commercial weight rests on the chubby shoulders of the baby “talent”. According to Mintel, sales of baby durables in the US were $2.7bn in 2011. The market is expected to grow 15 per cent between 2011 and 2016, reaching $3.1bn. The research group also says the number of household goods with “baby” in the product description increased 80 per cent between 2008 and 2012 – from 180 launches to about 330 last year.

Parenting magazines catering to working mothers, lifestyle for fathers and “green” parenthood, are no longer just on the newsstands but online, on apps. All require photographs. Lee Southey, art director for Junior and Practical Parenting magazines, says: “There is an increased demand for more images of babies, more shoots, for more and more products and fashion ranges.”

In recent years designer labels such as Hugo Boss, Chloé, Fendi, Marc Jacobs and Stella McCartney have all added children's ranges. A classic Burberry check dress for a newborn retails at ·110 while a Dior padded jacket goes for almost ·400. Last month London hosted the first global fashion week devoted to children. Should your baby's odour need some enhancement there are perfumes too – Burberry's Baby Touch and Bulgari's Petits et Mamans, soon to be joined by Dolce and Gabbana.

The emotional appeal of babies for advertisers is potent, says Patti Williams, an associate professor of marketing at Wharton School, University of Pennsylvania. “They immediately evoke a kind of empathy and engagement, especially from parents. Images of babies have emotional power and the ability to draw a viewer in and to keep a viewer's attention.”

It is Ms Salzinger's task to defuse the pressure from the financial expectations resting on the infants. “Babies need a quiet set. They need people not to be nervous around them. They're like sponges. If you're agitated, so are they. I tell the adults to relax. It's not good if the baby looks around at anxious adults, they'll end up crying.” Often she will take the infant off the set for some quiet time in order that the adults can calm down. To make a baby cry she might take a toy away or encourage a parent to play with their child and then leave.

Yet while the opportunities presented by baby and parenting products have increased, advertising and editorial budgets have been cut. Often the role of baby wrangler will be eliminated.

Ms Salzinger thinks it is a false economy. “Everyone on the set has a job·.·.·.·It means we have different mindsets. A stylist wants to keep pulling the shirt down. They can't do my job, which is pulling faces and keeping the kid happy.”

Economic constraints also mean that the days of specialist photographers are over. “Now they have to do everything,” she says. “They aren't so used to working with kids. They aren't factoring in naps to the day. They haven't brought baby wipes.” Part of her job is to educate the photographers. “They sometimes have toddlers balancing on a table without thinking of laying cushions on the floor. Or they put loud baby music on. We don't need that, we need some quiet so I can connect with the baby calmly.”

As a freelancer she is paid a day rate, earning most for print advertising and television commercials and least for editorial and catalogue work. She says her rates are similar to those of a photo stylist.

Before wrangling, Ms Salzinger worked as a studio manager for commercial photographers as well as a photographer's assistant, so she knows some of the technical aspects of a shoot: “I know where the babies need to look to get the lighting right.” Other baby wranglers come through teaching. Raised in New York, which is still her home, Ms Salzinger studied social anthropology. Both her parents are research psychologists and she sometimes calls her mother, a specialist in child development, for advice.

She does not feel comfortable speaking about the commercialisation of childhood and parenthood because she is not a parent. “I've heard a lot of different things and would have to leave that to the social scientists who can do controlled studies.”

However, she does refuse to work on shoots that encourage the sexualisation of young girls. “In any case, those photographers don't tend to want a wrangler. They don't want the girls to smile, they want them to look adult. It irks me.”

Acknowledging that the children she works with are there to sell something, she does, however, “like to think that [they learn] something. The younger babies sometimes take their first steps on camera while we are trying to get them to stand.

“The older kids can see that if they really try they can do it. And it is something they accomplish on their own – so it makes them feel cool.”

The parents generally leave her alone to get on with the job. Though she has had to disappoint one grandmother determined that her perpetually crying baby would be a star. “In the end I had to take her by the hand and lead her off the set.”