We all know about postpartum depression, but have you heard of postpartum anxiety?

Postpartum anxiety plagues just as many moms as postpartum depression, but not as many know about it. 

This type of anxiety paralyzes moms from functioning the way they normally would, said Karen Kleiman, founder and director of The Postpartum Stress Center in Pennsylvania. 

Between 14-15% of postpartum women report anxiety symptoms — the same as postpartum depression. Both conditions fall under Perinatal Mood and Anxiety Disorders (PMAD), which include mood and anxiety symptoms during and after pregnancy. Perinatal means these feelings can come during pregnancy, too. 

Why does this happen?

No one really knows. Researchers at the University of North Carolina are trying to figure it out by studying women between 18 and 45 who recently gave birth. But, their focus appears to be depression-focused. 

Some believe when the placenta is delivered, an abrupt change in hormones triggers a change in the brain, said Ann Smith, president of Postpartum Support International. We already know women's brains shrink during pregnancy. But, that doesn't explain mood disorders that occur during pregnancy. 

What are the symptoms?

"The most distressing of all anxiety symptoms can be negative unwanted thoughts of harm coming to the baby," Kleiman said in an email. "Typically, women will obsess over these thoughts and worry that they are an indication that something is terribly wrong, that they are psychotic, or that they shouldn’t be a mother, or that their baby should be taken away. But scary obsessive thoughts are anxiety-driven and actually extremely common."

Experts stress thoughts associated with postpartum anxiety are just that — thoughts that would never become actions. Psychosis is completely different; that is when people hear voices or see images telling them to do harmful things that seem friendly. Postpartum anxiety thoughts are "horrifying to you" and "you are fully aware this is a thought," Smith said

Other symptoms are often associated with paralyzing fear that affects everyday life. A baby brings a host of change for all moms. But, a concerning difference comes when moms aren't able to enjoy their quality of life and relationship with their newborn. 

"You don’t know how you’re going to make it from Wednesday to Thursday," Smith said.

Chrissy Teigen on postpartum depression:'It can happen to anybody'

Hayden Panettiere:Postpartum depression didn't make me a bad mother

What are the noticeable signs?

Women suffering from postpartum anxiety often don't want to leave the house and interact with others. So, those closest to them should be aware of changes in behavior. Here's what to look for:

Insomnia. Smith said this is the No. 1 sign something is wrong. Obviously, a newborn throws off normal sleep schedules, but if Mom can't sleep when baby does sleep, Smith said it's a red flag. 

Not eating. Those suffering from anxiety can feel like they've "had a thousand cups of coffee," Smith said. When people are in this fight-or-flight mode, appetite is often suppressed. 

Avoiding the baby. Moms might not want to touch the baby or change the baby. When they are with the baby, they might avoiding carrying the baby, paralyzed by fear. They also aren't going to want to drive the car with the baby alone. 

Sickness. Women might suffer from chills, nausea, numbness, dizziness, increased heart rate, palpitations, chest pressure, rapid breathing and stomach problems, Kleiman said. Some of these could be signs of a panic attack.

What's important to remember is "it's a biological illness, rather than a mental illness," Smith said. 

'I felt literally terrified':Mothers find support for their postpartum depression, anxiety and fear

More:American moms don’t breastfeed long. Here’s why.

Can it be treated?

Absolutely. "There is really effective treatment for all of this," Smith said. "Everybody can get better."

Mild cases of postpartum anxiety can be treated with the help of a support group, talk therapy and/or cognitive behavioral therapy. Moderate to severe cases require a combination of medication and therapy, Smith said. 

"Medication is highly effective with these illnesses, far more effective than with other mental issues," Smith said.

How to get help.

There is a risk of suicide with postpartum anxiety and any mood disorder. Anyone with a wish to end their life, should go to an emergency room immediately. If loved ones notice a mom who is showing odd, out of the ordinary behavior (especially seeing, hearing or believing things that aren't real), they also need help right away. 

"Stay with that mother," Smith said. "Never leave somebody like that alone. That’s when tragedy happens."

If you're thinking about suicide or know someone who is, can call the National Suicide Prevention Lifeline 24/7 at 1-800-273-8255. You can also text the  Crisis Text Line at 741-741 to connect with a trained crisis counselor right away.

Those looking for treatment for postpartum anxiety or PMAD should seek a women's health specialist with perinatal psychology training. Postpartum Support International can connect moms or loved ones with trained professionals. Connect with them online or by calling 1-800-944-4773.

"There is no harm in calling and talking a trained volunteer," Smith said. "This probably isn’t going to get better by itself."

Follow Ashley May on Twitter: @AshleyMayTwitter