By the time the average American child is potty trained, her parents will have shelled out upwards of $2,000 on diapers. That's more than 27 billion disposables consumed nationwide each year.
The battle was pitched decades ago. In 1960, Pampers aired its first television commercial, riffing on "This Little Piggy," and touting Pampers' seven layers of material designed to hold in whatever came out of baby's bottom.
Five decades later, Pampers are about half as bulky, the company said.
Diaper companies spend millions of dollars every year to design the thinnest and most absorbent product, trying to gain loyal customers along the way.
Procter & Gamble, Pampers' owner, granted "Nightline" access to the company's never-before-seen research and development center in Cincinnati, Ohio.
Here, more than 500 scientists, chemical engineers and seamstresses are trying to improve the look, feel and effectiveness of their products.
Their work is top secret. High-level executives don't even have access to every room. Digital locks control all laboratory doors, restricting access only to those who need to enter. And the locks track all comings and goings.
"This is serious business," said Kerri Hailey, associate director of research and development. "Absolutely, security is serious business everywhere. It's diapers."
Pampers' scientists work on prototypes for new diapers, which are tested for things like how they feel, stretch-ability, flexibility, durability and how they smell -- before and after baby does his business.
"We want to make sure that as babies are scooting around and moving, that the product stays together as its intended," Hailey said.
And that's all before they put real babies to work testing the products in real time.
In the "fit and load" test, babies stand on what looks like a treadmill and are fitted with diapers. Testers then watch them play to make sure they are comfortable in the nappies.
Then they load them up with a bubbly clear concoction designed to mimic urine.
Researchers test each diaper for how much it can take before leaking. They take detailed measurements, X-ray, and even create 3-dimensional computer models.
Data is compiled and compared, and researchers pour over their findings, looking for even the smallest gaps.
After all, one little wrinkle could mean messy mayhem for a mom on the go.
And then, once a diaper model has been thoroughly tested in the R&D center, they test it again. Moms are sent home with new products to test out. After using the diapers on their babies, the moms weigh the soiled diapers and send them back to Pampers.
Those dirty diapers are picked apart and studied. They are even sniffed in the name of science.
One unit is dedicated strictly to studying the diapers efficacy for baby's bowel movements. Why smell a stinky diaper?
"What we do is try to imagine and measure everything moms and dads experience with our products and so that includes applying and fitting well,'' said Hailey "But it also includes what is the scent experience that they get in the beginning, in the middle, in the end."
Pampers tests its diapers around the world.
"We do this every day,'' said Hailey. "So much so that in the past year we tested with over 40,000 consumers around the world."
So when dozens of mothers complained on Facebook about Pampers' new Dry Max diapers, claiming extreme diaper rash, including reports of chemical burns, the folks at Pampers were shocked.
"There's been no data to link the Dry Max to diaper rash," said Hailey. "Dry Max has been tested on over 20,000 babies."
The Internet swirled with theories about what was going on. Some speculated that either Pampers' competitors or environmentalists in favor of cloth diapers were behind some of the accusations.
Meanwhile, the diaper war between Pampers and Huggies intensified with Huggies' launch of a little shock-and-awe: a limited edition diaper that looks like blue jeans.
The company's commercial showed a toddler in a button-down shirt and jeans diapers, strutting down a foreign street as all eyes are on him.
"When it's number two, I look like number one,'' the boy says in an accented adult voice over electronic music.
The commercial quickly went viral. Its tag line was: "The coolest you'll look pooping your pants."
"Over one million consumers have actually gone onto YouTube to play the commercial for themselves," said Robert Thibault, president of Kimberly-Clark's North American Infant, Baby & Child Care business, maker of Huggies.
Huggies said sales skyrocketed upwards by 15 percent, almost overnight.
Pampers quickly fought back, releasing its special Cynthia Rowley designer diapers available at Target.
What every diaper company knows is that if they can get mom excited about about a new product, she'll switch brands. That is no easy task. Diapers buyers are extremely brand loyal -- starting from day one.
Studies show that if a mother is given a particular brand in the hospital, she is likely to use that brand for as long as her baby is in diapers.
So, both companies regularly sell their diapers to hospitals at a discount, hoping to hook customers early. Pampers claims it has contracts with about 95 percent of hospitals.
To win the diaper wars, companies know they have to win the hearts and minds of mommies. Billions of dollars are riding on those adorable bottom lines.