Everything you need to know about your fourth trimester

Congratulations! You birthed a tiny human. However, you haven’t crossed the pregnancy finish line just yet. You still need to navigate the fourth trimester – the first three months after delivery. The notion of the ‘fourth trimester’ was coined by Dr Harvey Karp, a paediatrician who believed human babies are born three months too early and need 12 weeks to adjust to life on the outside.
 
The fourth trimester is also a time of significant change for new mums. Besides adapting to no longer being pregnant, you’re learning to care for a new baby. Needless to say, a lot is going on.
 

Hormonal changes during the fourth trimester

 
The fourth trimester is characterised by swirling hormones – some help you bond with your baby; others can make you feel weepy and overwhelmed. While this shift may be distressing, it’s completely normal to experience emotional fluctuations a few weeks after birth, so try not to worry too much.
 

Oestrogen

 
After birth, your oestrogen levels plummet, which can lead to vaginal dryness, postpartum hot flushes, and mood changes.
 

Progesterone

 
Like oestrogen, progesterone drops dramatically after birth. Progesterone has a calming effect on mood, so low levels can cause emotional lability postpartum.
 

Oxytocin 

 
Although oxytocin (the 'love hormone’) plays a critical role in labour, it hangs around in postpartum, too. It helps you bond with your baby and protects against postpartum haemorrhage.
 

Prolactin 

 
Prolactin is known as the 'mothering hormone’. After delivery, progesterone dips, increasing prolactin receptors in the mammary glands and allowing milk secretion through the nipples to feed your baby.
 

Your baby's developments during the fourth trimester

 
Your baby grows and develops considerably in the first three months. During the fourth trimester, their neck becomes stronger; their head can eventually turn from side to side when placed on the abdomen; they can follow lights, faces, and objects; and they can open and close their hands. They may even begin to imitate sounds.
 

Common symptoms

 
Every woman experiences the fourth trimester differently – much of it will depend on the type of delivery you had (easy, difficult, vaginal or caesarean). Still, here are some of the most common symptoms.
 

Vaginal bleeding

 
Postpartum vaginal bleeding is extremely normal. Your body is simply shedding excess blood, mucus, and tissue that lined your uterus during pregnancy. You’ll probably have a heavy flow for 3-10 days and may experience spotting for up to six weeks.
 
Make sure you have enough sanitary pads on hand. If you soak through two pads an hour for more than an hour or two, call your doctor immediately, as it may indicate a postpartum haemorrhage.
 

‘Baby blues’

 
Navigating hormonal fluctuations, the physical toll of birth, sleep deprivation, and adjusting to life with a newborn can be overwhelming. If you’re feeling anxious or low for the first few weeks after birth, don’t worry – the ‘Baby Blues’ are completely normal and can affect 80% of women after delivery (1).

However, if these feelings persist or you start to experience panic attacks, excessive anxiety, loss of interest in your newborn, or a constant urge to cry, please speak to your GP or midwife as you may have postnatal depression. With the right support and guidance, you’ll start to feel yourself again.
 
You can learn more about supporting your mental health in postpartum here.
 

Constipation

 
If you’re struggling to pass a bowel movement after birth, you’re not alone. Constipation is common in the fourth trimester, especially if you’re worried about aggravating any perineum pain. 
 
Eating plenty of fibre-rich food (fruit, vegetables, whole grains, legumes, nuts, and seeds) and drinking enough water should help to get things moving. You may also want to try the natural soluble fibre Fructo-Oligosaccharides or FOS, derived from chicory root, which supports intestinal health. 
 

Fatigue

 
Having a baby is exhausting. Besides the physical burden of labour, navigating sleepless nights and the stress of looking after a newborn can take a toll on your energy levels. 
 
Don’t be afraid to ask for help! Lean on your partner, family, friends, and neighbours. And make life easy for yourself – there’s no need to keep the house pristine, host guests, or write thank you cards. Equally, try to sleep when your baby sleeps. And eat regular nutrient-dense meals to fuel you.
 

Other symptoms

 

• Abdominal cramps

• Sore perineum

• Difficulty urinating

• Haemorrhoids

• Body aches

• Night sweats

• Engorged breasts

• Sore nipples

 

What nutrients are important during the fourth trimester?

 
Your newborn isn’t the only one who needs nurturing at this time. After carrying your baby for nine months and navigating the dramatic experience of labour, you need plenty of nourishment, too. Healthy, nutritious food can heal, ground, and help your body return to its pre-pregnancy state, so it should remain a top priority in the fourth trimester.
 
You can learn more about optimising your postpartum nutrition here.
 

Iron

 
Since you lose considerable iron-containing blood during childbirth, replenishing your stores is vital. Iron plays a crucial role in energy production, cognitive function, and immunity in postpartum. Dietary iron also provides a steady mineral supply to your baby via breastmilk, supporting growth and development. 
 
You can find haem iron – the most bioavailable (readily absorbed) – in animal foods like red meat, poultry, seafood, fish, and dairy. Plant-based foods, including nuts, seeds, whole grains, and green leafy vegetables, contain non-haem iron, which is harder to absorb. However, combining plant iron with vitamin C – naturally present in cabbage, spinach, tomatoes, and citrus fruits – can support mineral uptake. 
 
Aside from increasing dietary iron, you may also wish to take a supplement to reinforce reserves after birth.
 

Magnesium

 
Magnesium is another critical mineral in postpartum, playing a role in muscle recovery, psychological health, and nervous system function. It also reduces tiredness and fatigue, which is especially helpful when dealing with less sleep. New mums often have low magnesium levels, so you must get enough in your diet.
 
You can find magnesium in dark leafy greens, avocado, whole grains, beans, nuts and seeds. However, if you’re concerned about your intake, you may wish to take supplemental magnesium. 
 

Iodine

 
Iodine is an essential trace mineral that supports infant brain development and physical growth (2). And yet, many women who breastfeed fall short, especially those on vegan diets.
 
Seafood, seaweed, milk, yoghurt and cheese are rich sources of iodine. Still, we recommend supplementing with iodine to help you meet the increased need in postpartum. 
 

Zinc

 
An essential trace mineral, zinc contributes to normal immunity, cognitive function, and wound healing, making it vital post-pregnancy. Breastfeeding women are at an increased risk for zinc deficiency, so ensuring a plentiful intake in postpartum is critical. 
 
You can find zinc in oysters, red meat, shellfish, whole grains, and fortified breakfast cereals. However, if you’re concerned about your levels, we recommend taking a supplement. 
 

Vitamin C

 
Both vaginal and caesarean births require intense recovery, tissue repair, and wound healing, which is why a reliable intake of vitamin C is important.  
 
Citrus fruit, tomatoes, peppers, berries, and dark leafy greens are excellent sources of vitamin C. You could also take supplemental vitamin C to replenish your stores.  
 

Vitamin D3

 
Involved in immunity, bone health, and general well-being, vitamin D3 is essential for new mums. Infants obtain some vitamin D3 from their mother’s breastmilk, so if you’re breastfeeding, there’s even more reason to stay on top of your intake. 
 
Alongside increasing dietary vitamin D3 – found in liver, fatty fish like salmon and tuna, egg yolks, and fortified dairy products – and getting sun exposure where you can, the NHS recommends breastfeeding women take a vitamin D3 supplement containing 10µg throughout postpartum to safeguard levels (3). 
 

Vitamin B12

 
Vitamin B12 is also important post-pregnancy. It supports red blood cell development, DNA synthesis, and energy. Research suggests low maternal vitamin B12 stores may cause developmental delays in breastfed infants (4). 
 
The best sources of vitamin B12 derive from animal products, including red meat, liver, salmon, and eggs. However, plant-based foods, like mushrooms, yeast extract, and fortified cereals, also contain small amounts. 
 
Still, it can be challenging to get enough vitamin B12 from diet alone – especially for vegans – so we recommend supplementing throughout postpartum to support your health and your baby’s. 
 

Choline

 
If you choose to breastfeed, getting enough choline is vital. Choline plays an essential role in infant brain and nervous system development (5). Without enough nutrient-dense, choline-rich breastmilk, your baby will leach from your own stores, so it’s important to keep your reserves topped up. 
 
Although meat, poultry, fish, eggs, dairy, nuts, seeds, and whole grains are good dietary sources of choline, we recommend taking supplemental choline to meet the increased need in postpartum.
 

Omega 3 fatty acids

 
Essential fatty acids are also critical in postpartum. Evidence suggests babies of mothers with higher concentrations of docosahexaenoic acid (DHA) – a long-chain essential fatty acid – in their breastmilk have better visual and brain development (6). A plentiful intake of DHA may also support your emotional wellbeing after delivery (7). 
 
Oily fish like salmon, anchovies, and mackerel are the best sources of DHA. Eating two servings per week can help support your omega-3 consumption in postpartum. 
 
You can also find essential fatty acids in plant foods, including walnuts, chia seeds, and flaxseeds. These plants contain alpha-linolenic acid (ALA), another essential fatty acid that’s converted into DHA in small amounts in the body. 
 
If you’re concerned about your omega-3 intake in postpartum, it’s worth taking a high-strength fish oil or vegan alternative derived from plant-based microalgae to cover any shortfalls. 
 

Take a bespoke multi

 
There’s a lot to think about as a new mum – nappy changes, breastfeeding, and navigating the many night-time stirrings. If you want one less thing on the to-do list, perhaps consider taking a high-strength, comprehensive multivitamin. It’s a simple and easy way to ensure a reliable intake of the most essential postpartum nutrients to support your health and your baby's development. 
 

Weight loss in the fourth trimester

 
The first few months of postpartum are about bonding with your baby and recovering from childbirth – not losing weight – so there’s no need to put any unnecessary pressure on yourself at this time.

Midwives generally recommend most mothers start considering weight loss around three months postpartum. But always take a kind, gentle, and sustainable approach. You can learn more about losing postpartum weight safely here.
 

Top tips for the fourth trimester

 

• Be kind to yourself

• Take each morning, afternoon and evening as it comes

• It takes a village to raise a child – turn to your friends and family for help

• Make time for self-care

• Focus on rest and recovery

• Embrace change

• Pat yourself on the back – you’re doing great!

• Ask for professional help if you need it

 

Find out more

 
If you found this article useful, you can read more postpartum guidance on our health blog. Alternatively, please get in touch with our team of expert Nutrition Advisors, who are on hand to provide free, confidential advice.


References:

1. National Childbirth Trust. (2019b). "The baby blues: What to expect." NCT (National Childbirth Trust). [online] Available at: https://www.nct.org.uk/life-parent/how-you-might-be-feeling/baby-blues-what-expect.

2. Harvard T.H. Chan. (2021). "Iodine." The Nutrition Source. [online] Available at: https://www.hsph.harvard.edu/nutritionsource/iodine/.

3. nhs.uk. (2023). "Breastfeeding vitamins - Start for Life." [online] Available at: https://www.nhs.uk/start-for-life/baby/feeding-your-baby/breastfeeding/healthy-diet-when-breastfeeding/breastfeeding-vitamins/.

4. Keskin, EY , Keskin, M , Karaibrahimo?lu, A Association of Maternal Vitamin B12 Status with Infant Findings and Neurodevelopment in Vitamin B12-Deficient Breast-fed Babies. 2022

5. Obeid R, Derbyshire E, Schön C. (2022) "Association between Maternal Choline, Fetal Brain Development, and Child Neurocognition: Systematic Review and Meta-Analysis of Human Studies." Adv Nutr. 13(6):2445-2457.

6. Society for Research in Child Development. (2009) "Supplementing Babies' Formula With DHA Boosts Cognitive Development, Study Finds." ScienceDaily. ScienceDaily, 17 September 2009.

7. Freeman MP, Hibbeln JR, Wisner KL, Brumbach BH, Watchman M, Gelenberg AJ. (2006) "Randomized dose-ranging pilot trial of omega-3 fatty acids for postpartum depression." Acta Psychiatr Scand. 113(1):31-5.

 

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