When she became pregnant, Ms. Martin called her local hospital inquiring about the price of maternity care; the finance office at first said it did not know, and then gave her a range of $4,000 to $45,000. “It was unreal,” Ms. Martin said. “I was like, How could you not know this? You’re a hospital.”

Midway through her pregnancy, she fought for a deep discount on a $935 bill for an ultrasound, arguing that she had already paid a radiologist $256 to read the scan, which took only 20 minutes of a technician’s time using a machine that had been bought years ago. She ended up paying $655. “I feel like I’m in a used-car lot,” said Ms. Martin, a former art gallery manager who is starting graduate school in the fall.

Like Ms. Martin, plenty of other pregnant women are getting sticker shock in the United States, where charges for delivery have about tripled since 1996, according to an analysis done for The New York Times by Truven Health Analytics. Childbirth in the United States is uniquely expensive, and maternity and newborn care constitute the single biggest category of hospital payouts for most commercial insurers and state Medicaid programs. The cumulative costs of approximately four million annual births is well over $50 billion.

And though maternity care costs far less in other developed countries than it does in the United States, studies show that their citizens do not have less access to care or to high-tech care during pregnancy than Americans.