You are walking down the stairs with the baby and a picture flashes into your mind of falling. You are giving a bath and think, what if I let go? You are chopping vegetables and an image appears that you would never tell anyone about. Then comes the horror, and the question: what is wrong with me?

These are intrusive thoughts: sudden, unwanted thoughts or images, often about harm coming to the baby. Research suggests most new parents have them at least sometimes. They are one of the ways a brain that has just become responsible for a fragile new person scans for danger.

What they mean, and what they do not

• They are unwanted. The fact that they horrify you is the point: they go against everything you want.
• Having them does not mean you secretly want them to happen, or that you are dangerous.
• Parents who have intrusive thoughts tend to become more careful, not less.
• They are not the same as postpartum psychosis, which is rare and involves losing touch with reality.

When they are worth getting help for

• They come often, feel impossible to shake, or take up a lot of your day.
• You start avoiding things because of them: bathing the baby, using knives, being alone with the baby, the stairs.
• You feel driven to check, count, pray, seek reassurance or repeat things to make the thought go away.
• They come with constant anxiety, low mood or trouble sleeping.
• That pattern can be postpartum OCD or postpartum anxiety. Both are common and very treatable, and perinatal specialists see them all the time.

What helps

• Tell someone. Many parents are afraid to say it out loud. Providers who work in perinatal mental health know the difference between intrusive thoughts and intent, and hear about them often.
• Therapy, especially cognitive behavioral therapy with exposure and response prevention (ERP), is very effective for postpartum OCD.
• Medication can help too, and a prescriber can talk through options that work with breastfeeding.
• Try not to argue with the thought or push it away. Noticing it ("that is an intrusive thought") and letting it pass usually works better than fighting it.
• Protect sleep. Exhaustion makes the thoughts louder.

• Find a postpartum therapist near you
• Find a perinatal psychiatrist near you
• Postpartum psychosis: the signs, and what to do

For dads, partners and family

If she tells you about a thought like this, the most helpful thing you can say is "thank you for telling me, that sounds awful, and it does not change how I see you." Unless you see the emergency signs below, try not to react with alarm or start watching her with the baby. Offer to help her find a perinatal therapist and to go with her to the first appointment.