It may sound scary, but this is a perfectly normal and important milestone in pregnancy. Your baby’s head is engaging (dropping) when it starts moving down into your pelvis to prepare for birth.

“With a first baby, the head generally starts to move down into the pelvis from about 36 weeks but some babies get moving downwards well before that. Then, week by week, until you go into labour, the head moves down until it is engaged," says Rachel Fitz-Desorgher, a retired midwife with over 35 years’ experience in infant feeding, active births and working with parents.

In first pregnancies, engagement can happen anywhere between 34 and 38 weeks. When this happens you may notice your bump move down a little.

Here's everything you need to know about your baby's head engaging.

What happens when my baby's head is engaged?

“When your baby's head is engaging, you might be told that baby is ‘at the brim’, which means that the baby's brow is just into your pelvis and the head can't wiggle and look around quite so much anymore,” says Rachel.

What does my midwife mean by 1/5th, 2/5th or 3/5ths engaged?

"When midwives and GPs feel your bump to see if baby is engaging, they think of the head being in 5ths, and then describe how many 5ths of the baby’s head have gone down into the pelvis. The very widest part of the baby’s head is at the 3/5ths point down from the top of the head.

"Ask your midwife or GP if they are telling you how many fifths are already in your pelvis or how many can still be felt out - 3/5ths out is, of course, 2/5ths in," adds Rachel.

Here's what the measurements mean

• 5/5 Your baby's head has not yet engaged. It is sitting above the brim of your pelvis.

• 4/5 Your baby's head is starting to enter your pelvis, so only the top or back of the head is felt.

• 3/5 At this point, the widest part of your baby's head has moved into your pelvic brim and is engaged.

• 2/5 More of the baby's head has passed over your pelvic brim.

• 1/5 Most of the baby's head is deeply engaged.

• 0/5 Your baby entire head can be felt and seen by your midwife/doctor and is a key step before birth.

But why is this measured? The answer is that if the widest part of the baby’s head can get into the pelvis, there is a better chance that your new arrival will come out the other side at birth without too much difficulty. Still need a little help to understand the measurements? Take a look at Midwife Marley's video here.

How can I tell my baby's head is engaged?

The symptoms for each mother and baby vary, with some mums not getting any symptoms at all when their baby goes into their pelvis.

However, Rachel says, some mums could notice several different symptoms:

“Always tell your midwife or GP what you are experiencing so that you can be properly checked to make sure that all is well and that your symptoms are simply the baby going downwards,” she adds.

Symptoms of baby’s head engaged

• Breathing: You'll start to feel less pressure on your lungs, which means you might breathe more easily.

• Bladder: You'll need to urinate more because your baby is pressing on your bladder.

• Bump: You'll notice your bump will appear lower in your abdomen.

• Bowel movements: You may feel constipated.

• Discomfort: You may feel more pressure in your pelvic area, or discomfort around your cervix and back pain.

• Vaginal discharge: You may notice more vaginal discharge.

When does baby's head engage?

The time when a baby’s head engages varies from mother to mother, according to Rachel.

There are several different factors that can affect the speed at which the head will drop in and engage, from the size and shape of your pelvis to whether you’re having your first baby or not. The way your baby is facing can also have an impact.

“With a first baby, the head generally starts to move down into the pelvis from about 36 weeks but some babies get moving downwards well before that,” she says. “Then, week by week, until you go into labour, the head moves down until it is engaged. Sometimes the engagement process is quick and sometimes it is slow. With a second or third (or umpteenth) baby, it is not uncommon for the baby to stay out of the pelvis, or just a little way in, until you get into labour. Then the baby goes into, through and out of the pelvis in one fell swoop in labour!”

My baby's head is engaged - how long until labour?

There’s no one-size-fits-all answer to the questions of how long it takes to go into labour once your baby has engaged.

Women vary enormously in their experience of labour, and the time it takes for engagement to happen can be extremely different, even with the same woman with different babies.

“People will tell you that once the head is engaged, you will go into labour soon,” says Rachel. “This is not true, nor is it true that you won't go into labour if the head hasn't engaged. However, with a first baby, the head going down (even if it doesn't fully engage) is a good sign that your pelvis is a good size for birth.

“Don't panic, though, if this is your first baby and the head hasn't gone down by term - it might simply be that baby needs to wiggle into a better position as labour gets going and then will get down into and through your pelvis quite nicely. Your midwife or GP is the best person to advise you, not your mates on Facebook!”

Can I encourage my baby to engage quicker?

There are all sorts of advice for women about how to encourage their babies to engage, but according to Rachel, it’s debatable whether these recommendations actually work.

• “Many people will tell you to lie on your left-hand side in bed"

• "And to be careful not to sit too far back in your sofa"

She continues, "but good evidence for this is a little thin on the ground and many women start to fret and feel guilty when they do ‘all the right things’ and the baby hasn't dropped."

“Your body is beautifully evolved for growing and birthing your baby, so relax, stay as comfortable as you can in bed at night and when sitting at work or at home, and your baby will go into and through your pelvis all in good time. Remember that your midwife and GP are experts in understanding your pregnant body and how a baby grows and moves down. So write down all your worries and questions day by day and share them at every visit.”

About the expert

Rachel Fitz-D is a retired specialist midwife and works as a baby and parenting consultant. She has four grown-up sons and two grandchildren. She regularly presents at The Baby Show and is the author of “Your Baby Skin To Skin”.

Maria Martin is Digital Group Editor for Yours.co.uk and Motherandbaby.com. She is a mum-of-two with a passion for helping women from all walks of life – from supporting breastfeeding mothers with expert advice to encouraging conversations about mental health. In her professional role, she has over 10 years' experience in the digital world, including editing articles, focussing on SEO, social media engagement, picture researching and video editing.