The 12 weeks after birth deserve their own name
What changes for your body, your mood and your baby from week 1 to week 12, and when to ask for help.
Quick answer
The fourth trimester is the first 12 weeks or so after your baby is born, when your body recovers from pregnancy and birth while you and your baby adjust to life outside the womb. ACOG uses the term and recommends that postpartum care during this time is an ongoing process, with contact within 3 weeks of birth and a full check no later than 12 weeks. Expect bleeding for up to about 6 weeks, broken sleep, big emotions and a gradual return of strength.
Pregnancy is split into three trimesters, but recovery does not end on the day you give birth. The phrase fourth trimester describes the stretch of weeks after birth in which mum and baby are both going through rapid change. ACOG's Committee Opinion 736 lists the challenges women commonly face in this period, including lack of sleep, fatigue, pain, breastfeeding difficulties, stress, mental health changes and urinary incontinence, and calls for care that is tailored and continues over time.
is roughly how long the fourth trimester lasts; ACOG recommends a full postpartum visit no later than this (Committee Opinion 736, 2018)
is how long the NHS says bleeding after birth (lochia) can continue
of new mums experience the baby blues, which NHS services describe as starting around day 3 and passing within about 2 weeks
The fourth trimester, week by week
Every recovery is different, and a caesarean, a tear or a long labour can change the pace. Use this as a general map rather than a deadline.
| Weeks | Your body | Your mind | Your baby |
|---|---|---|---|
| Week 1 | Heaviest bleeding, afterpains, sore perineum or wound, milk coming in | Euphoria, shock, tearfulness from around day 3 | Frequent feeds, lots of sleep in short stretches |
| Weeks 2 to 3 | Bleeding lighter and browner, stitches healing | Baby blues usually easing | Growth spurts and cluster feeding are common |
| Weeks 4 to 6 | Bleeding settling, more energy on good days | Exhaustion can build; watch for low mood that is not lifting | More alert, first social smiles often around 6 weeks |
| Weeks 6 to 8 | NHS postnatal check with your GP | A chance to talk about mood, sleep and sex | Baby's 6 to 8 week check |
| Weeks 8 to 12 | Gradual return to gentle exercise once cleared; core and pelvic floor rebuilding | Routines start to feel more familiar | Longer awake periods; some longer sleep stretches |
What is happening to your body
Bleeding and your womb
Lochia is the normal bleeding and discharge as the lining of your womb sheds. The NHS describes it as heavy and bright red at first, gradually becoming darker, lighter and then pale, and it can last up to about 6 weeks. Soaking a pad in an hour, large clots, a bad smell or fever are reasons to call your midwife or GP the same day.
Your tummy muscles
Some separation of the tummy muscles is normal after pregnancy. In the Sperstad study, 60% of women had diastasis recti at 6 weeks after birth, and the rate fell steadily over the year. Our diastasis recti healing timeline explains what that means for you.
60%
45.5%
32.6%
Source: Sperstad et al., British Journal of Sports Medicine, 2016.
Your pelvic floor
Leaking when you cough or sneeze, or a feeling of heaviness, is common in the early weeks but is not something you have to accept long term. The NHS recommends starting gentle pelvic floor exercises soon after birth if you feel able. If symptoms persist, ask your GP about a referral to a women's health physiotherapist.
What is happening to your mood
The baby blues are common and short-lived: tearfulness, anxiety and feeling overwhelmed that start a few days after birth and fade within about two weeks. Postnatal depression is different. If low mood, anxiety or intrusive thoughts last longer than two weeks, start later, or stop you enjoying anything, tell your midwife, health visitor or GP. If you ever feel you might harm yourself or your baby, seek urgent help through NHS 111, 999 or A and E.
How to make the fourth trimester easier
- Lower the bar. Rest, food, fluids and feeding come first. Everything else can wait.
- Keep appointments in one place. Our postpartum appointment schedule lists the usual checks for you and your baby.
- Ask for specific help. Meals, washing and an hour of baby-holding are worth more than visitors who need hosting. If you are weighing up paid help, read is a postnatal doula worth it.
- Track the basics. A simple daily log of sleep, bleeding, pain and mood makes it easier to spot changes and explain them to your midwife.
- Rebuild slowly. Breathing and pelvic floor work come before crunches or running. Our guide on when you can start working out after birth sets out a safe order.
Want the fourth trimester on paper?
The Postpartum Recovery Planner is a printable fourth-trimester planner for tracking rest, recovery, appointments, mood and the small wins, so nothing important slips through the cracks. It costs $8 as a one-time download, and code GLOW20 takes 20% off. Take a look at the Postpartum Recovery Planner. Results vary from mum to mum, and it does not replace your midwife or GP.
Frequently asked questions
How long is the fourth trimester?
It is usually described as the first 12 weeks after birth. ACOG recommends contact with your care provider within 3 weeks and a comprehensive postpartum visit no later than 12 weeks, though recovery for many mums continues beyond that.
Who came up with the term fourth trimester?
The idea was popularised by paediatrician Harvey Karp, who used it to describe a newborn's adjustment to life outside the womb. ACOG and other health bodies now use it for the mother's recovery too.
Is it normal to still bleed at 5 weeks postpartum?
Yes, the NHS says bleeding after birth can last up to about 6 weeks, getting lighter over time. Contact your midwife or GP if it becomes heavy again, smells bad, comes with large clots or you develop a fever.
When should I worry about my mood after birth?
Baby blues usually pass within about two weeks. If low mood, anxiety or intrusive thoughts last longer, start later or feel overwhelming, speak to your midwife, health visitor or GP. In an emergency, call 999 or go to A and E.
When can I exercise during the fourth trimester?
Gentle walking and pelvic floor exercises can usually begin soon after birth if you feel able. Most mums are advised to wait until after their 6 to 8 week check, and longer after a caesarean, before returning to more demanding exercise.
Sources: ACOG Committee Opinion 736, Optimizing Postpartum Care, 2018; NHS, Your post-pregnancy body (bleeding and pelvic floor); NHS trust patient information on baby blues and postnatal depression; Sperstad JB et al., Diastasis recti abdominis during pregnancy and 12 months after childbirth, British Journal of Sports Medicine, 2016; Karp H, The Happiest Baby on the Block, 2002.
This article is general education, not medical advice. Mumma Glow is not affiliated with any organisation named here. Results vary from mum to mum. If you have any concerns after birth, see your GP, midwife or a women's health physiotherapist.