Depression and mental health problems affect up to 20% of all pregnant women, according to a leading pregnancy charity.
Tommy's, which funds research into miscarriage, stillbirth and premature birth, wants to reinforce the message that there is plenty of support available for pregnant women.
As a member of the Maternity Mental Health Alliance, Tommy's has launched a #MumTalk campaign encouraging women to share their mental health stories with one another.
Tommy's midwife Anna Nella has shared her top tips for looking after your mental health in pregnancy.
Speaking to getwestlondon to mark World Mental Health Day on Tuesday (October 10), Anna said: "Everybody is going to have some stress in pregnancy.
"It may come from overwhelming feelings about the pregnancy or not feeling sure about what's going on."
She added: "Pregnancy doesn't stop us from becoming unwell and developing mental health issues so it's really important to recognise that you will feel up and down.
"If you feel that things are overwhelming and that you're not coping it's good to go and see your GP as a first point of call."
Anna said midwives are "pivotal" in helping mums look after their mental health.
"When you go to your first appointment with the midwife, in the first 12 weeks of pregnancy, they'll ask you specific questions about your mental health," she said.
"It’s important to be honest with the midwife about how you feel. She won’t criticise you, and she can help you get support or treatment if you need it."
Top tips for mental health in pregnancy
Go for a walk
Getting your endorphins or "happy hormones" going can be great for your mental health.
Eat a balanced diet
What you eat can affect your mood and energy levels - it's important to eat a varied and balanced diet during pregnancy.
This can be hard if you've been suffering from nausea but try and avoid foods high in fat and sugar and opt for slow burning carbohydrates like wholegrain rice and bread instead.
Get enough sleep
This can be difficult at some stages of pregnancy but getting enough sleep (eight hours a day) is fundamental to having good mental health.
Talk to someone
It’s normal to have periods of feeling worried or low when you’re pregnant or after birth, but if these feelings don’t go away its important to talk to your midwife or GP about how you're feeling so they can help you.
If you have an existing mental health issue
Speak to your GP
Ideally you would do this before you get pregnant to talk about pre-conceptual care so that if you are on medication this can be adjusted or changed.
If you become pregnant when you hadn't been planning to you should speak to your GP as soon as possible.
Jane Brewin, CEO of Tommy's, said: "Mental health needs parity with physical health in pregnancy.
"Depression and mental health problems affect up to 20% of all pregnant women. And left untreated, these conditions can have lasting effects on the emotional and physical health of both mother and baby.
"Nonetheless, the information and support provided to pregnant women on physical wellbeing far outweighs that offered on mental wellbeing. Diagnosis and treatment of mental health problems is less likely to happen during pregnancy than any other time.
"As well as developing our mental health information, resources and case studies, we have signposted to it from our general pregnancy information so that women who have no previous experience of mental health problems are not excluded."
She added: "Talking openly about mental wellbeing is the first step towards reducing the stigma around it. We want all pregnant women to be aware of the steps they can take to keep themselves well during pregnancy, both mentally and physically.
You can access mental health information, case studies and support from the Tommy's website here.