Fewer women in their 20s are choosing to become mothers, leading to an overall birthrate decline in the U.S. But the birth rate among U.S. women age 30-45 is rising according to the latest federal data. CHARLY TRIBALLEAU/AFP hide caption

CHARLY TRIBALLEAU/AFP

Sarah Harris was 36 years old when she gave birth to her daughter Bridget last year. She describes motherhood as equal parts joy and exhaustion. "When you have a baby in your mid-30s, what you gain in wisdom and experience you also lose in terms of energy," Harris says with a laugh.

Harris, who lives in Vermont, was laid off from a job four months after Bridget was born. She says she's still figuring out what her career and her life will look like with a child. Harris thinks a lot of women are like her. They're wrestling with financial uncertainty and waiting much later to choose pregnancy.

There's also the high cost of raising a child, which Harris said convinced her that one is enough.…