What would trigger a woman to throw her baby out of a building?

Prosecutors say Sonia Hermosillo drove her infant son to the fourth-story of a parking garage, removed a special helmet he wore for a medical condition and tossed him over the edge. She then validated her parking ticket and drove away, they say.

The 7-month-old boy with deep brown eyes died Wednesday, the same day his 31-year-old mother was charged with murder and felony child abuse.

Hermosillo's husband says that she suffered from severe postpartum depression and couldn't accept that her only son had two unusual disabilities, one of which required him to wear a special helmet to reshape his head.

"There is no grudge against my wife. Don't judge her poorly. She was truly ill," Noe Medina said tearfully in his native Spanish on Wednesday. "Understand the pain that I am in ... I lost my son and now I don't want to lose my wife. I have to keep going on for my two little girls."

Postpartum depression affects up to 20 percent of new mothers and can be triggered or worsened by stresses such as a traumatic childbirth experience, disabilities in the infant or an unsupportive home situation, experts said.

Most of these women have the "baby blues," a bout of depression that goes away within a few weeks, but a tiny fraction — about .01 percent — develop postpartum psychosis, said Stephanie Morales, a licensed marriage and family therapist who specializes in perinatal mood disorders.

By all accounts, Hermosillo was a wonderful mother until the birth of Noe Medina Jr. this year.

The native of Mexico had two older daughters, ages 7 and 10, and she doted on them as a stay-at-home mother while her husband worked in construction, according to neighbors who knew her before she gave birth to her third child.

They said she was involved in her daughters' schooling and walked them to class in the family's working class La Habra neighborhood every day, although she spoke little English.

When she learned she was expecting a son, she was excited, said Sonia Herrera, an upstairs neighbor whose daughter played with Hermosillo's children and attended the same school.

After the boy's birth, Hermosillo became withdrawn and serious, she said. Herrera wondered if she might have postpartum depression.

Medina said his wife was hospitalized for postpartum depression in June after she said she didn't want the boy. The baby had been diagnosed with congenital muscular torticollis — a twisting of the neck to one side — and wore a helmet to help correct his plagiocephaly, also known as flat-head syndrome, The Orange County Register reported.

The day before Hermosillo was arrested, Herrera saw her taking out the trash.

"She was different. She was serious," Herrera said. "I asked her many questions, and she just said 'Yes' or 'No.'"

Studies suggest that Hispanic women suffer from slightly higher rates of postpartum depression than the general population because many are first-generation immigrants, Morales said. They also are removed from the social and cultural support systems that surround childbirth in many Latin American cultures, she added. A language barrier also prevents some immigrant women from getting help.

"In many of the pueblos and smaller towns of Latin America, especially in Mexico, women will be quarantined for 40 days and 40 nights after birth," said Morales, who specializes in counseling Hispanic women with postpartum depression. "Women move to this country and ... there's some discussion that by losing some of the cultural traditions that have been built in over the years, women no longer have the strategies for staving off some of that."

Hermosillo's husband said his wife took medication after her hospitalization and had seen a therapist for the first time on Monday. Later that day, she scooped up the baby while her husband was watching their daughters, and left their second-story apartment.

A panicked Medina called 911 to report his wife and son missing. La Habra police has declined to release that call, citing the pending investigation.

Most postpartum depression can be treated with medication, therapy and good family support, but stress can worsen the situation, said Morales, the specialist.

"We know that mothers who have children with special needs, they have a higher rate of postpartum depression," said Morales, who was speaking generally and has not treated Hermosillo. "Any kind of stressor can exacerbate these symptoms."

Authorities say she threw the baby from a parking garage at Children's Hospital of Orange County, where the boy had been undergoing physical therapy twice a week. The boy didn't have an appointment that day.

A witness saw the baby falling through the air, and several people, including a doctor, called 911, said Sgt. Dan Adams, an Orange police spokesman. One witness thought a child had dropped a doll when he saw the baby falling through the air, said Scott Simmons, who is prosecuting the case.

Surveillance video showed Hermosillo's sport utility vehicle with an empty child seat leaving the parking structure a short time later, Adams said. The license plate was traced to the Hermosillo home, the sergeant said.

A police officer driving past Children's Hospital about four hours later spotted Hermosillo driving on a street about 100 yards from the crime scene and arrested her, Adams said. Hermosillo remained held without bail at the request of immigration officials, who say she's in the country illegally.

Women who have been through postpartum depression said they can understand Hermosillo's actions through the lens of their own mental illness. Tiffany Benton, of San Jose, suffered postpartum depression after the birth of both of her children, now 8 and 11.

Benton, 39, said she would dream about pushing her infant in a stroller down a steep slope and letting go of the carriage. She said she was afraid to bathe her daughter because she didn't trust herself not to drown her.

Benton went three weeks without sleeping at one point and was hospitalized for two weeks after the birth of her younger child when she began hallucinating, she said.

Now healthy, Benton takes medication and goes to therapy, but she has cut her medicine dose in half and hopes to taper off completely with time.

"I was just a disaster emotionally. I felt like I was going crazy and I was having panic attacks," Benton recalled in a phone interview. "My husband had no clue what was going on. He was like, 'Oh, you'll be fine tomorrow,' and I was like, 'No, no, I won't.'"

Based on reporting by The Associated Press.

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