KEELY AND JASON Krantz have been buffeted by hardships lately -- the loss of a paycheck and a sharp scaling-down of their lifestyle.

But the turmoil arises from a happy event -- the birth in April of their first baby. The Krantzes, both 28 years old, are committed to having Ms. Krantz stay home as a full-time mother.

Married, college-educated parents like the Krantzes are leading a nascent shift, reported last month by the Census Bureau, toward mothers of very young children staying home. While it's too soon to call a trend, the bureau says that for the first time in 25 years, the proportion of working mothers with children under one year old posted a decline, to 55% in 2000 from 59% in 1998. Whether the blip does become a trend depends largely on the resiliency and commitment of couples like the Krantzes.

Based on monthly interviews since March, here is how they're faring so far:

Spring 2001: The Krantzes, who have been married two years, know that having an at-home parent entails sacrifices. While dating, they shared warm memories of their own mothers' presence when they were young, greeting them at the school bus.

But as Keely enters her ninth month of pregnancy, they face some New Age hurdles. Like many dual earners, they've been alternating the breadwinning burden to cushion economic swings.

AT THE MOMENT, Keely's paycheck as public-relations director at edocs, a Natick, Mass., billing-software concern, is paying most of the bills, including college loans and payments on their Cambridge, Mass., condo. It is enabling Jason to launch a promising new business he co-founded in 1999, Infinata, an Arlington, Mass., marketing-analytics software concern. "He's an entrepreneur at heart," Keely says.

Just 13 months earlier, a booming economy would have eased the Krantzes' choice. Now, with a venture-capital drought shrinking Infinata's financing options, the Krantzes are looking at a sharp drop in household income, a prospect Jason admits is "extraordinarily stressful." To shield each other, each tries to avoid talking about their financial anxieties.

Keely's job offers a psychological payback as well. She loves helping launch new products. And the new workplace flexibility makes it harder for her to quit. Edocs co-founder Jim Moran, who praises Keely's work ethic, makes several offers of flexible setups after childbirth, offers she finds hard to refuse. Keely assembles a spreadsheet of business contacts and presses Jason to get her home computer set up for e-mail. "It scares me a little to think about losing touch," she says.

On April 27, Keely is relieved when the long limbo of pregnancy is over. After 13 hours' labor, she gives birth to a healthy girl, Aidan. "It puts things in perspective, to hold a newborn baby," Jason says.

As he shoulders all the complex roles of today's working fathers, Jason changes his routine, starting his workdays before dawn to allow himself a few evening hours with Aidan and Keely. He manages to juggle it all, but at a cost. Trying to read one night, he falls asleep with his face wedged between the pages of his book.

In May, Keely hits a low point. Exhausted by round-the-clock infant care and the challenges of breast-feeding, she laments, "I quit my job for motherhood and I'm not even good at it!"

SUMMER: SEEING no end to the economic slowdown, the Krantzes begin shaping solutions. They whack 30% from their budget, clipping coupons, joining a wholesale club and slashing cable television. One afternoon, they spend two hours researching where to buy the cheapest diapers. As they cut back, Keely says, "there's a little romance in the struggle."

She is gaining confidence as a mother. Jason helps by noticing small milestones in Aidan's development and praising Keely's role. On a visit to her old office, Keely is given a completed project she started last spring. Once, she would have rushed to add it to her portfolio; this time, she throws it away. "I hope I don't regret doing that," she thinks later.

After weeks of discussion about it, the Krantzes take a painful step: selling their condo. They'd hoped to keep it as a rental property after buying a house, to help Keely stay home. Instead, they pay off debt and move to a two-bedroom rental.

Autumn: Though the nation is reeling from terrorism and a slumping economy, the Krantzes have emerged stronger. Infinata's strategy of building a strong customer base is paying off and Jason is drawing a bigger salary. Their apartment, in Watertown, has all the conveniences nearby. "We've turned a major corner," Keely says.

Edocs makes yet another offer to lure Keely back, a part-time, work-at-home deal she once would have coveted. She turns it down. Though she feels pangs of envy at her friends' career milestones, she's savoring the private joys of motherhood -- seeing Aidan's face light up after brief separations, seeing her calm reaction to strangers. "I really know now that I wouldn't trade this for that," she says.

Though unnerving, the terrorist assault has affirmed the value she places on family. So far, the Krantzes have been able to create a haven of their own at home. "We've survived a lot of different blows," Keely says, "and come out still strong."