The first three months after birth – often called the fourth trimester – are a time of huge transition for both you and your baby. While pregnancy and birth are behind you, the early postnatal weeks bring their own challenges, changes, and powerful moments of bonding.
During this phase, your baby is adapting to life outside the womb. They still need constant care, closeness, and nourishment. And as a new parent, you’re navigating recovery, sleep deprivation, and a whole new rhythm of life.
Here’s what to expect from the fourth trimester, plus practical tips to help you feel supported and informed during these early days.
What Is the Fourth Trimester?
The fourth trimester refers to the first 12 weeks after birth, a period of physical, emotional, and developmental adjustment. Your baby has been snug in the womb for nine months – a warm, responsive environment. Once born, they depend on you completely as they adjust to the outside world.
Your newborn is biologically wired to stay close to you. In many ways, they still behave as if they’re in the womb – craving your scent, voice, warmth, and presence. This is why holding, feeding, and comforting your baby frequently is not only normal, but essential for their development and your bonding.
Sleep in the Fourth Trimester
Newborn sleep can feel unpredictable and exhausting. Your baby may sleep up to 18 hours a day, but rarely in long stretches. Their internal body clock (circadian rhythm) hasn’t developed yet, so day and night mean little to them.
Key things to know:
- Most newborns sleep in 2–3 hour bursts, including through the night
- They need help falling asleep: cuddles, rocking, or feeding often help
- Some prefer to sleep in arms or close to your body
Babywearing and Skin-to-Skin
Your baby finds security in being held close. Babywearing in a sling can help mimic the feeling of the womb, keeping them calm while allowing you to move freely.
- Look for ergonomic slings or carriers and follow baby sling safety guidance
- Skin-to-skin contact helps regulate your baby’s temperature, breathing and heart rate
- It also supports milk supply and bonding
Feeding in the Fourth Trimester
Newborns have tiny tummies and need to feed frequently – often every 2 to 3 hours. Breastmilk is easily digested, so breastfed babies may feed even more frequently, including overnight.
Look for feeding cues like:
- Rooting or turning their head
- Sucking fingers
- Lip-smacking
Responsive feeding (feeding when your baby shows signs of hunger) helps establish a strong milk supply and supports baby’s growth.
The Emotional Rollercoaster
It’s completely normal to feel overwhelmed in the early weeks. The combination of hormonal changes, lack of sleep, physical recovery and emotional adjustment can be intense.
You might feel:
- Tearful or irritable (often known as the 'baby blues')
- Anxious about getting things “right”
- Isolated or disconnected
If these feelings persist beyond two weeks, speak to your midwife, GP or health visitor. You could be experiencing postnatal depression – and support is available.
Baby Sleep at 3 Months
By the end of the fourth trimester, your baby may begin to develop a more regular pattern:
- Sleeping slightly longer stretches at night (but still waking for feeds)
- Napping more consistently during the day
Every baby is different. Some sleep in longer blocks, while others wake frequently. It’s still completely normal to have broken sleep for many months.
One study found that over 50% of babies at 6 months still don’t sleep for 8 hours at a time.
Try to nap when you can – research shows daytime naps help mental and physical recovery when night sleep is limited.
Sharing Sleep Space Safely
The Lullaby Trust and Unicef recommend babies sleep in the same room as their parents for the first 6 months. This helps reduce the risk of SIDS and supports easier night-time feeding.
If you choose to co-sleep, follow safe sleep guidance:
- Place baby on their back on a firm, flat surface
- Keep pillows, blankets and duvets away
- Never co-sleep on a sofa or armchair
- Avoid bedsharing if you’re overtired, have drunk alcohol, smoked, or taken medication
- Don’t co-sleep if your baby was premature or low birth weight
Midwife’s Top Tips
- Accept help from friends and family - even small things make a big difference
- Don’t worry about routines in the early weeks - follow your baby’s lead
- Look after your own recovery with rest, nutrition, and gentle movement
- Cuddle and connect with your baby as much as you like - you can’t spoil them
- Seek support early if you’re struggling emotionally or physically
The fourth trimester can feel all-consuming, but it’s also a precious time to bond, recover, and begin to grow together.
Keep your baby close, respond to their needs, and lean on your support network. There is no perfect way to parent - trust your instincts, take things one day at a time, and remember: you are doing a brilliant job.
