Around 15 percent of new mothers experience post-partum depression and should seek medical help at the earliest opportunity, say experts

New mothers are supposed to experience a lot of emotions, but tears of sadness at the new baby aren't a good sign.

Many new mothers are depressed after birth, a situation made even harder because most people seem to have so little understanding of the problem.

About 15 percent of all women are affected.

Women battling with the problem are often told: "Just sleep it off." But it's better to go to a doctor, since the earlier the depression is confronted, the easier it is to get it under control.

Doctors make a distinction between baby blues, post-partum depression and fear disorders.

"About 50 to 80 percent of all women have days where they cry," says Corinna Reck of the Center for Psychosocial Medicine at the University of Heidelberg Hospital in Germany.

A lot of this can be explained by the fact that, after birth, there are such changes in hormonal levels that it will cause mood shifts, says Tamme Goecke, a chief doctor at the Women's Clinic at the University Clinic of Erlangen.

These mood swings can last about two weeks, on average, before going away on their own.

Should they last longer, then there is the possibility of post-partum depression or a fear disorder, says Reck, head psychologist at a special mother-child station.

The deeper the post-partum depression, the harder it is for the women to concentrate and sleep.

Lethargy, listlessness, moodiness, lack of interest in previously enjoyed activities and general detachment are all symptoms.

Those symptoms are often described as the standard side-effects of the new demands of motherhood, Goecke says.

"They're just accepted and not recognized as serious signs of a burgeoning depression."

It might seem counterintuitive, but women who have been trying to have a child for a long time, have suffered miscarriages or have had complicated pregnancies are more likely to suffer from post-partum depressions, Goecke says.

"Our research shows that in normal births, where the mother has the sense of being in control, post-partum depression crops up less often."

But if a woman feels out of control in the delivery room, then the risk increases.

Those women are not the only victims of post-partum depression.

Especially at risk are young mothers and those who have had previous bouts of depression, live in a troubled relationship, or only get limited support from their partner, Goecke says.

"A non-treated depression increases the risk of further depressions," warns Stephanie Krueger, a professor at the Clinic for Psychiatry and Psychotherapy at Berlin's Charite Hospital.

"If a depressive mother has less interaction with her child due to her illness, then she can stunt the child's development in the long term," Goecke adds.

There are different treatment options for the problem.

Light depression can be treated with cognitive behavior therapy and interpersonal psychotherapy, reports the Institute for Quality and Efficiency in Health Care (IQWiG).

The first approach focuses on changing negative ideas and behavior.

The second alternative requires a therapist to work with the mother to consider possible lifestyle changes.

Medication is needed to combat medium to severe depression, says Krueger, who has researched the use of psycho-pharmaceuticals in postpartum depression.

"There is a series of antidepressants, which only show up in minute traces in breast milk, meaning mothers can nurse as normal."

But the IQWiG is more cautious.

It says more study is required before determining what dangers the child could face if the mother is taking medication, says Hilda Bastion of the IQWiG.

That means mothers have to be sure to talk to their doctors about risks and side-effects. Krueger also recommends that mothers suffering depression seek out a psychiatrist.

"These women aren't just having a bad day, but an illness that needs treatment."