Kelly Wallace is CNN's digital correspondent and editor-at-large covering family, career and life. Read her other columns, and follow her reports at CNN Parents and on Twitter.

(CNN) They are tragedies impossible to comprehend. Over the past three months, three New York City mothers have allegedly tossed their babies out windows, and they've fallen to their deaths.

In the most recent case, Tenisha Fearon, 27, reportedly screamed "We're all going to die" in front of her other children before allegedly throwing her 6-month-old daughter out the window of her sixth-floor apartment.

Fearon was charged with murder in the death; she's in police custody and was ordered to undergo a psychiatric evaluation, according to CNN affiliate WABC . En route to her first court appearance, CNN affiliate WCBS reported, she made a comment to her godmother, Louella Hatch.

"She said, 'I tried to tell you Miss Louella,' but I don't understand," Hatch said.

The godmother said she had seen the family one day before the deadly incident and everything seemed OK. She now believes her godchild, whom she said usually appeared happy and confident, was suffering from postpartum depression but never spoke up.

"My belief is she was sick and just didn't tell anybody," Hatch said. "This is a disease and nobody detects it."

We don't know what Fearon might be experiencing. What we do know is that as many as 20% of women -- one in five -- will suffer from some form of depression, mood or anxiety disorder during or after pregnancy, according to experts I spoke with who work with women.

The spectrum of illnesses goes beyond depression to include anxiety, obsessive compulsive disorder, post-traumatic stress disorder, bipolar disorder and in the rarest and most serious cases, postpartum psychosis. Extreme cases of that illness tend to garner national media attention, although postpartum psychosis affects a very small number of moms -- just one or two of every 1,000 new mothers.

Women in low-income communities are more at risk for postpartum depression or any other form of pregnancy-related mental illness during or after pregnancy, according to the research.

And yet, for a host of reasons including access, financial barriers, stigma and cultural differences, these mothers are often not getting the treatment they need.

The stigma of mental illness

Lynne McIntyre, manager of the maternal health program at Mary's Center for Maternal and Child Care in Washington, D.C., can cite plenty of examples of how the stigma of a mood or anxiety disorder during or after pregnancy keeps women from seeking treatment. Mary's Center provides care regardless of a patient's ability to pay, and most of the women who use its services have low incomes and come from Latino, African American and East African communities.

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"I have had African American friends tell me, so it was firsthand, they were on the receiving end of messages including, 'That's a white woman's disease. We don't get that,' " said McIntyre, herself a survivor of postpartum depression. She was miserable and suicidal when her older son was born nearly 11 years ago. That experience led her to devote her life to helping women with the disease.

She has heard from a woman who said that people at her church asked her, "What have you been doing wrong that God would do this to you, that he would let this happen to you?" Other women have heard comments such as "Why did you have a baby if you didn't want one? You should just sort of get yourself together and take care of your baby and don't be so self-indulgent,' " said McIntyre, a mother of two.

It serves people from multiple backgrounds and countries. Depression is also taboo in many cultures, said Marty Hartman, executive director of Mary's Place in Seattle, an overnight shelter for families. (It's not affiliated with Mary's Center.)It serves people from multiple backgrounds and countries.

"It brings shame upon you and your family forever if you were to talk about the depression and so that is a definite hurdle to get over," she said.

Women in low income communities may not step forward to seek help out of fear of what might happen to their babies.

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"There's a fear that if one opens up ... that child protective services would become involved, and it's not uncommon for women to fear the extreme that their children will be taken away from them," said Dr. Judy Greene, director of women's mental health at Bellevue Hospital Center in New York.

Sonia Murdock, co-founder and executive director of Postpartum Resource Center of New York, said she and her colleagues often have to reassure women that their children won't be taken away if they seek help.

"We are helping to educate these women and to connect them then to the help and the support they need to get better, and to let them know it's a sign of good parenting when they are taking care of themselves so they can be there to best help take care of their baby," Murdock said.

Growing awareness of postpartum depression

Murdock devoted her life to raising awareness about these issues after her sister battled postpartum psychosis 20 years ago. When her sister's husband took her to the emergency room after she had a psychotic break, nobody -- from the psychiatrists to the social workers -- gave her family a clear diagnosis, said Murdock.

She finally started to understand what was happening to her sister when a janitor came up to her in the hospital's family room. The janitor told her that he stopped his own sister from throwing her baby out the window and that her sister would be OK.

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"I always say he was our family's first guardian angel," Murdock said.

But 20 years later, there are still far too many women and men who don't understand that mood and anxiety disorders during and after pregnancy are real. They are among most common medical complications related to having a baby, according to the American College of Obstetricians and Gynecologists

"People come to me and they're like, 'I'm a social worker and I suffer from postpartum depression and I had no idea,' so if a social worker's telling you that, we know there is a problem. We have a crisis on our hands," said Nitzia Logothetis, founder and executive chairwoman of the Seleni Institute, a nonprofit focused on serving the reproductive and maternal mental health care needs of women.

"So I think it's really about changing the conversation and getting the word out, educating people."

Seleni does bimonthly trainings with social workers, nurses, doulas -- anyone who is involved with looking after pregnant women or women who have given birth -- on how to treat, diagnosis and screen for depression or other mental illnesses.

That same kind of training takes place at Mary's Center and helps reach women it might not reach otherwise, said McIntyre, who regularly trains everyone from the medical providers to the paraprofessionals who do home visits to the mental health care therapists.

"You never know who is going to be that staff member or that provider that she really feels connected to, that she is going to let her guard down too a little bit," said McIntyre.

"It might not be the pediatrician that she feels like she can open up to. It might be the midwife that she runs into in the hallway when she brings the baby to the pediatrician because we're all in the same place or it might be the home visitor that for some reason she feels a connection with the person who is a paraprofessional."

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Normalizing postpartum depression and the other mental illnesses associated with pregnancy -- and communicating how mood and anxiety disorders are among the most common complications of pregnancy -- are vital to getting women to feel comfortable opening up, they said.

"It doesn't mean that you are a bad mom. It doesn't mean that you don't love your baby. It doesn't mean that you are not taking good care of your baby but ... I would say it's an illness. It's an illness you can get in pregnancy just like pre-eclampsia or just like gestational diabetes and we can treat it and you're not alone," McIntyre said.

But, even if a woman is aware of postpartum depression and feels comfortable getting help, she might not have the financial means or the transportation to get help.

"There is a huge gap," said Hartman of Mary's Place in Seattle. "Whether it's not having child care, you can't go to the appointment because you don't have a bus ticket to get to the appointment. You don't have gas in your car, and you can't get to the appointment. All of those things are real and those prevent people from accessing the care that they need.

"I can't tell you how many people won't go if they have a co-pay and they just don't have the money."

Models of success

At Bellevue Hospital Center in New York City, the maternal mental health program is integrated into the general women's health care program, which increases the chances of reaching a women in need. Every pregnant patient at Bellevue is seen by a social worker or a case worker, who will do an initial screening to assess history of mental illness and current symptoms.

If a patient is found to be experiencing any mental health issues, they are referred to the psychiatrist in the women's health program and monitored throughout their pregnancy and after delivery.

"I think what's unique about our program is that we are integrated into the women's health services so a lot of places will have the screen-and-refer-out model, but when you refer people out to a standalone mental health facility, there's a big drop-off in the percentage of women who will actually make it to that first appointment," said Greene, the director of women's mental health at Bellevue.

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Women who show symptoms after they give birth, rather than during pregnancy, would be referred to the mental health program, she said. They coordinate with ob-gyns and with the pediatric department in order to reach moms.

"They'll notice that something's not quite right and they'll refer to us," said Greene.

The success of a program like this is based on a simple reality: People will go to a facility for medical issues, but it's harder to get people in for mental health, said Logothetis, the founder of Seleni. "There's a stigma attached to it, but ... you can incorporate it into something that people already have to do. So if you're pregnant, you have to go to your OB a certain number of times, you have to get weighed. It's just a much more practical way of getting to the mental health portion."

At Mary's Center in Washington, the facility offers two free, ongoing support groups, one in English, one in Spanish, that women can join any time. They also provide direct psychotherapy and psychiatric services to moms.

Just like at Bellevue Hospital Center, women go to Mary's Center for all their health care needs, which increases the chances that a woman who is struggling with mental illness will be identified. Pediatricians are trained to screen for mood and anxiety disorders, and not just go with their gut.

"Chances are, she's going to hide it. She's going to try to. She feels guilty. She feels like she's the only one. She feels like she's failing as a mother," McIntyre said.

What to say to a new mom

The universal message that mental health advocates try to convey about anxiety and depression during or after pregnancy are three simple sentences, said Murdock of the Postpartum Resource Center of New York: "You are not alone. You are not to blame. You will feel better and be well with the help."

Letting women know how mental health issues during and after pregnancy are the one of the most common complications shows them they are most definitely not alone. Hearing that researchers have not pinpointed one particular cause helps them remove any blame. Knowing it is a fully treatable illness can encourage them to get the help they need, she said.

To get that message to a wider audience, Murdock's organization implemented a public awareness campaign called "Ask the Question." It involves asking new parents how they're doing and how they are feeling, and then listening for the response. If there are concerns, the next step would be giving them the support or encouragement to get help, and being aware of the resources that are available for them.

"Ask them the question, 'How are you doing? How are you sleeping? ... How does it feel to have a baby?' " said Logothetis of Seleni. "It's amazing when you actually start asking questions, people start to open up and you can then suggest that they try to see somebody."

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I, for one, have long said to new mothers "Enjoy this magical time." But as I've learned more about postpartum depression and other mood and anxiety disorders during and after pregnancy, I've tried to stop saying it or writing it on a friend's Facebook page. Those words can make a woman feel bad if she is not having a magical time. It also doesn't give me an opportunity to determine if my friend is struggling or needs help.

Signs of struggle could be a new mother who is crying a lot, has trouble sleeping, has a loss of appetite or is eating too much, has panic attacks, is angry or irritable, seems overwhelmed or seems a bit off, said Murdock.

We all can play a role, she said. "I call it the perinatal mood and anxiety disorder safety net and every person in society plays a role because we just never know with having this information who we may come across and change the path of somebody's life when we are being supportive, being understanding, being educated.

"For some women," Murdock said, "getting this information or not getting this information could be a matter of life and death."

If you or someone you know needs help, please contact any of the following resources: