GEOFF BENNETT: The U.S. fertility rate hit another record low last year, with families having fewer children and a growing number of women opting out of motherhood altogether.

A new large-scale study might offer some clarity.

American mothers have seen a stark drop in their mental health.

Stephanie Sy is back with that story.

THERESA ENGLE, Ohio Mother: He is very rambunctious.

He is smart and he is funny.

STEPHANIE SY: Theresa Engle wouldn't trade being a mother to Theo for anything, but that doesn't mean it's easy being a parent to a child with autism.

THERESA ENGLE: He has days where he's very negative, and you just kind of absorb it and then you're thinking of all the things going on that you have no control over.

And I don't sleep well.

I really don't.

I have that -- the 3:00 a.m. thing where you're like, so many things are wrong and how can I fix it, and just feeling kind of powerless.

STEPHANIE SY: Taking care of Theo was a full-time job.

And without a paying job, the high cost of living is only creating more stress.

THERESA ENGLE: Things have become so precarious.

We don't get help.

We do have Medicaid.

That's it.

And the safety nets are slashed, cut.

It doesn't feel good.

STEPHANIE SY: This Ohio mom is far from alone.

We spoke to mothers throughout the country across race and socioeconomic status.

They told us they're overwhelmed, stressed out and lacking in necessary support and resources.

MEAGAN RICO, Kansas Mother: I lay awake at night worried about my children's future and my future and where things will go if worse things happen in our economy or if things get more difficult for us.

MICHELLE BRANDT, South Carolina Mother: Sometimes, my anxiety is so great, I feel stuck.

And it was actually my best friend, she was like, Michelle, I haven't heard you laugh in two months.

And she was like, I think you might have postpartum depression.

KRISTINA BERARDI, New York Mother: Maternity leave can be very isolating.

You're home all the time with a little person who wants and needs everything, but at the beginning can't even smile at you.

Currently, I feel stressed about is just the economy.

THERESA ENGLE: Women tend to internalize and put others first.

And our health, all aspects of our health become unimportant.

STEPHANIE SY: A recent study published in "The Journal of the American Medical Association" found a worrying trend.

Data from nearly 200,000 mothers of children of all ages found a decline in mental health.

Less than 26 percent of mothers reported excellent mental health in 2023, down from roughly 38 percent in 2016.

Mothers describing their health as just good rose from roughly 19 percent to 26 percent, and those who rated their mental health fair or poor rose from 5.5 percent to 8.5 percent.

JAMIE DAW, Columbia University Mailman School of Public Health: It's unusual to see such a big change over such a short period of time.

STEPHANIE SY: Jamie Daw is an assistant professor at Columbia University Mailman School of Public Health and co-author of the study.

Was that something you saw equally distributed across sort of the measures that you looked at?

JAMIE DAW: Yes, these are really the kinds we're seeing across the board.

The thing to point out, though, is that not all groups were starting from the same baseline, right?

So you could have a similar decline, but we know that single moms, those whose children were insured by Medicaid, those of lower education in particular had much higher rates of fair and poor mental health.

STEPHANIE SY: Another significant outlier, mothers of multiracial children, who saw steep drops in their mental health.

Aesha Mustafa, mother of a 1-year-old daughter, says it can add additional mental strain.

AESHA MUSTAFA, Michigan Mother: The comments of like, you're going to have trouble with that hair growing up and like being prepared for these racialized comments, and like how do I handle that is a whole thing that makes motherhood as a Black woman more difficult and also raising a Black interracial child.

MELISA SCOTT, Certified Nurse Midwife, Michigan Medicine: A lot of places, pediatricians office are asking mothers to check boxes about their mental health, but then what?

There's nothing else.

Is she still active?

STEPHANIE SY: In between performing ultrasounds and blood pressure checks, certified nurse midwife Melisa Scott noticed something in her patients in Ann Arbor, Michigan.

MELISA SCOTT: People feeling a sense of isolation, people feeling like, I wish I had some mom friends.

I wish I could talk to somebody about some of these feelings that I'm having of sadness around X, Y and Z, also feeling like, I'm not sure how to navigate this.

STEPHANIE SY: Many of Scott's patients are Black mothers, who have higher mortality rates, worse physical health outcomes, and also saw a decline in their mental health.

LATRESA WILEY, Our Village: Any words of wisdom that you would like to give these moms who will be soon bringing their babies into the world?

STEPHANIE SY: Tired of being unable to offer more support, Scott and her colleague, clinical social worker LaTresa Wiley, created a community for Black mothers beginning in 2019.

Our Village now includes over 200 moms and holds meetings twice a month in person and virtually.

MELISA SCOTT: We have rich women, poor women, all different types of women, some partnered, some unpartnered.

So it really presents a really diverse conversation.

And there is this unifying situation that happens because they're all Black women.

So it is very common that someone will say, I'm really struggling with X, breast-feeding.

And other women will come around here and just say, OK, how can I help?

There isn't the stigma that I see in a lot of mom spaces, even like mom blogs or Facebook or wherever.

STEPHANIE SY: Mustafa, who going into motherhood had a history of depression and anxiety, participates regularly in Our Village meetups.

AESHA MUSTAFA: Our Village has helped spark that joy of being in spaces with folks who look like me and then also making me get out in the community.

STEPHANIE SY: Do you think that mothers in general have enough support?

AESHA MUSTAFA: No, absolutely not.

I think, in general, across genders, parenthood is hard.

And then, with mothers, there's a lot of expectations of you control the domain.

So if you're out with baby, that baby's cold.

Why didn't you dress that baby?

That baby looks hungry.

Just constant criticism of how someone's doing that I don't see happening with dads, where with dads, it's like, oh, you took the kid to the library by yourself?

That's so great.

Look at you.

STEPHANIE SY: Whether it's from increased self-awareness, societal expectations or economic pressures, the mental health of mothers is a complex issue that Columbia researcher Jamie Daw says needs to be addressed.

JAMIE DAW: I would hope that our findings will help policymakers really prioritize this issue of supporting parents and not just early on in an early childhood, but throughout your parenting journey from zero to 18, and how this country could better support moms.

STEPHANIE SY: Until there is more support, moms like Theresa Engle's health will suffer.

THERESA ENGLE: I should be taking better care of myself, not skipping appointments.

This is more important than just being fit.

It's being here, being present.

STEPHANIE SY: Ultimately, it's not just the health of mothers at stake, but the children that depend on them.

For the "PBS News Hour," I'm Stephanie Sy.