More than one in 10 women in the UK develop a mental illness during pregnancy or in the year after giving birth.
But while most of us have heard of postnatal depression (PND), there are many more forms of perinatal mental illness people aren't aware of.
The Perinatal Mental Health Partnership says that ignorance about the symptoms of these conditions is "tragic, because if untreated, they can have a devastating impact on the women affected - and their families".
May is maternal mental health awareness month. Mental health experts want to highlight the range of emotional and psychological symptoms mums-to-be and new mums can experience and, most importantly, that support is available.
Here are the perinatal and postnatal mental illnesses everybody needs to know about:
Research suggests antenatal depression, or depression that occurs during pregnancy, may be even more common than postnatal depression. A history of stress and a pre-existing depressive illness can increase the risk of antenatal depression.
Symptoms include low mood, irritability, loss of interest, poor sleep and appetite, poor concentration, lack of energy, feelings of hopelessness and withdrawing from contact with other people.
Treatment includes trying to reduce any obvious causes, such as stress, as well as counselling and other psychological therapies. Only when the depression is severe will medication be recommended.
This common problem, which has affected celebrities including Gwyneth Paltrow and Adele, can start in the first year after giving birth and is more than just a case of the baby blues, when new mums might temporarily feel a bit down or tearful soon after giving birth.
Symptoms include those listed for antenatal depression, as well as difficulty bonding with your baby and getting no enjoyment from him/her, thinking you can't look after the baby, having frightening thoughts (possibly about hurting the baby) and thinking about suicide or self-harm.
If symptoms last more than two weeks, or start later than the first few weeks after birth, it may be PND, and you should talk to your GP or health visitor as soon as possible. Without help, symptoms can last for years, and there's lots that can be done to support you.
Advice is also available from the Mind helpline on 0300 123 3393 (or visit mind.org.uk).
Mothers who've had difficult deliveries have a higher risk of postnatal anxiety, which can develop gradually over time, and they're more likely to suffer from PND.
Symptoms include frequently feeling nervous or anxious, worrying, finding it difficult to relax or sleep, struggling to bond with the baby, restlessness, irritability, constantly checking on the baby, thinking bad things will happen to him/her, palpitations, rapid breathing, dizziness, excessive sweating, muscle tension and tingling or pain.
If you're experiencing some of these symptoms, talk to your midwife, health visitor or GP.
Studies suggest obsessive compulsive disorder is more common during pregnancy, or afterwards, than at other times in life, as mums are focused on the safety of their developing/new baby.
Symptoms include fear of contamination to the mother, baby or anyone in contact with the baby, intrusive thoughts, worries about harm, doubts about equipment, perfectionism and excessive tidying and cleanliness.
Occasionally experiencing some of these signs is normal for new mums. It's only when it becomes obsessive and starts having a wider impact on yourself, and possibly your family, that you should seek help.
This is a severe but rare mental illness, leading to extreme difficulty in responding emotionally to a newborn baby. It may occur at the same time as PND, and around half of mothers with postpartum psychosis already have a history of mental illness. The condition often starts in the first one to four weeks after the birth.
Symptoms include thoughts of harming the baby, delusions, hallucinations, a lack of emotional response, difficulty sleeping, changes in appetite, irritability, confusion, suicidal thoughts and the belief that the baby would be better off without you.
The mother may not want to admit to or talk about her feelings, but family members or health professionals who suspect psychosis should seek psychiatric help for them immediately.
Treatment may include hospitalisation, antipsychotic medication, antidepressants, electroconvulsive therapy and counselling.
Support is out there
The Perinatal Mental Health Partnership UK acknowledges there's still stigma surrounding negative emotional feelings while pregnant or after a baby's born, but says seeking support is really important, stressing: "Suffering from a perinatal illness can be difficult.
"But with the right help and support, women can and do recover.
"Reaching out and admitting they aren't feeling right in no way means they are weak or a bad mum. Absolutely not - it's incredibly brave of them to take the first step."
Dr Stephanie de Giorgio, a GP with the Perinatal Mental Health Partnership, who suffered with PND herself, says only half of women with maternal mental health problems are diagnosed, and points out: "Women are often reluctant to admit to feelings of negativity towards their pregnancy or baby for fear of being judged or having their babies taken away from them."
She says some under-pressure health professionals may not give women the time they need to share their feelings and be diagnosed, and adds: "Society expects mothers to enjoy motherhood, and admitting this isn't how you're feeling can make some women feel they've failed.
"However, a prompt diagnosis and treatment is important to ensure the woman and her baby, along with the rest of the family, can get off to the best start."
For more information, visit maternalmentalhealthalliance.org. The Perinatal Mental Health Partnership has also made a series of videos, which you can find on its Facebook page