During two decades as a delivery-room anesthesiologist, Valerie Arkoosh heard not just medical concerns from patients but their worries about life.

From mothers afraid to let their children play outside, or who lived in neighborhoods with no grocery stores as obesity rates were on the rise. From fathers worried they would lose their jobs if they took off to witness the birth of their child. From parents who worked 40 hours a week but increasingly struggled to make ends meet.

Her ability to help, she knew, had limits.

"When you live under anxiety and stress of that sort, it affects your health in ways that doctors can't fix," Arkoosh said.

It's a perspective that shaped her and now drives her in an unlikely second career: as the newly tapped leader of the state's third-largest county.

Arkoosh, 56, became chairwoman of the Montgomery County Board of Commissioners this month, taking the reins from Josh Shapiro, who will step down in January to become Pennsylvania attorney general.

Arkoosh becomes the first woman to lead the administration, overseeing a roughly $400 million budget and more than 2,000 employees in a county of more than 800,000 residents. She is also the only woman chairing a county government in the Philadelphia region.

The shift from doctor to politician and elected official may seem unusual. But to her and those who know her, it was a logical progression.

"I'm not surprised that she's doing so well" in politics, said fellow doctor and former coworker Sindhu Srinivas, director of obstetrical services at the Hospital of the University of Pennsylvania. "She just makes connections with people really easily, and people of all ages and races and ethnicities and backgrounds."

Arkoosh said her background as a doctor keeps her grounded while handling the stressful task of leading a large county.

"It affords me a perspective that a lot of my colleagues don't always have, because in my book if nobody died, it's really not that serious," she said.

Though she has long been politically active, serving on the Board of Commissioners is Arkoosh's first elected position.

The Springfield Township resident has a master's degree in public health. Her career as a practicing physician included chairing the anesthesiology department at Drexel University's medical school and working as a professor at the University of Pennsylvania's Perelman School of Medicine.

She joined the board of the National Physicians Alliance in 2007, and spent time in Washington in that role advocating for health-care reform.

In 2011, she joined Shapiro's transition team as he prepared to become commissioner, and chaired the County Board of Health from that time until she stepped down to run for Congress in 2014.

She lost that primary to the eventual general election winner, Rep. Brendan Boyle, but raised more than all her opponents and made her political mark.

When former Commissioner Leslie S. Richards stepped down last year to become state transportation secretary, Arkoosh was appointed to the seat. Last fall, she won a four-year term outright as the Democrats retained control of the administration.

Bruce L. Castor Jr., the Republican commissioner when Arkoosh was appointed, said he immediately liked her no-nonsense approach.

"If something bothered her, she would march into my office and tell me it bothered her," he said. "Working with Val was like working with a seasoned professional scientist, which in fact is what she is."

Arkoosh also gave Castor the only flu shot he's ever gotten, when she vaccinated her fellow commissioners at a public meeting last year.

Beyond giving shots, Arkoosh has brought a doctor's perspective to other areas of county government. She is overseeing the combination of several county departments into one health and human services department to streamline services and messaging, and make it easier for constituents to receive services.

State Rep. Mary Jo Daley (D., Montgomery) said she is impressed with Arkoosh's commitment, meeting constituents and attending community events.

"It's a big county just geographically also and it's got diversity with the inner-ring suburbs going out to agricultural areas," Daley said. "She's made it her business to really know about it."

Shapiro and Arkoosh have clashed at times with Joseph C. Gale, the new Republican commissioner who has been a vocal critic of the way they run county government.

Arkoosh said last week she hopes "everyone will be fully focused on governing" now that a tense election season is over. (A replacement to fill the third seat after Shapiro leaves will be chosen by Montgomery County Court with input from Arkoosh and the county Democratic chairman.)

Arkoosh said she has been willing to work with Gale since he took office in January, when she sat down with him and explained what she'd done to learn about county government as a newcomer. "I can only say that he did not do it as fully as I did when I began my transition," she said.

Gale wrote in an email last week that Arkoosh is "a very nice person," but criticized her for being in "lock step" with Shapiro and Democrats.

"It is to no surprise that her first undertaking as chairwoman is to raise county property taxes another 11 percent," he said.

Arkoosh is not the only elected official in her home. Her husband, Jeffrey Harbison, is president of the Springfield Board of Commissioners. The couple have three children: a 16-year-old son and 14-year-old twins, a boy and a girl.

While county commissioners are permitted to keep jobs in the private sector, Arkoosh treats the post as chairwoman, with a $90,846 salary, as a full-time position.

In an interview last week, Arkoosh did not rule out running for higher office one day. But she said she does plan to run for reelection in 2019.

"Val's going to continue to lead this board," Shapiro said after handing over his gavel to her, "for years in the future."