Iron and vitamins after birth

After birth, it is normal to feel tired. But when the tiredness does not go away, hair falls out heavily for months and energy does not return, it is worth looking at the body's reserves. Pregnancy, birth and breastfeeding use up iron, iodine and other vitamins, and many mothers reach the postpartum period with low reserves.

Iron is the most important point: anaemia affects 10% to 30% of mothers in developed countries, and many more have low reserves without anaemia. Iodine is essential during breastfeeding, and in Portugal a supplement is recommended. Vitamin D, B12 and omega 3 complete the list.

In this guide we explain why reserves fall, which signs to look for, which tests make sense and how to replace what is missing, safely and without unnecessary supplements.

Why the postpartum period depletes reserves

Three phases add up:

• Pregnancy. The mother's blood volume increases by about 50%, and the baby and placenta need iron, iodine and vitamins. Many women end pregnancy with low ferritin, even when taking supplements.
• Childbirth. Every birth involves blood loss, greater in a caesarean or a postpartum haemorrhage. Every millilitre of blood lost takes iron with it.
• Breastfeeding. Breast milk needs iodine, vitamin A, B12, DHA and other nutrients, which come from the diet or from the mother's reserves. As for iron, exclusive breastfeeding delays the return of periods, which helps to save iron; when periods return, the losses resume.

How many mothers have anaemia?

According to World Health Organization estimates, postpartum anaemia affects 10% to 30% of women in developed countries. In a Spanish study, 24.5% of mothers had anaemia 24 hours after birth (Ruiz de Viñaspre-Hernández et al., 2021). Iron deficiency without anaemia, that is, low reserves with normal haemoglobin, is even more common.

Why it matters

• Tiredness and lack of energy, on top of nights of poor sleep.
• Hair loss. Low ferritin is associated with hair loss in women, even without anaemia (Treister-Goltzman et al., 2022). Anaemia can also prolong the normal postpartum hair loss.
• Breastfeeding. Lower haemoglobin values have been associated with earlier stopping of breastfeeding.
• Mood. Several studies link anaemia with low mood in the postpartum period, although the relationship is not fully clarified.
• Next pregnancy. Starting a new pregnancy with low reserves increases the risk of anaemia.

Iron: the most important nutrient after birth

Signs that may indicate iron deficiency

• tiredness that does not improve with rest;
• pallor of the skin, lips or inside of the eyelids;
• shortness of breath or a racing heart on climbing stairs;
• dizziness on standing up;
• hair loss that goes on, brittle nails;
• difficulty concentrating;
• cravings for ice or unusual substances;
• restless legs at night.

Many of these signs are easily mistaken for the normal tiredness of caring for a newborn. That is why blood tests are important.

Ferritin: iron reserves

Haemoglobin shows whether there is anaemia. Ferritin shows reserves: it may be low long before haemoglobin falls.

The classic deficiency threshold is 15 ng/mL. But several studies show that a threshold of 30 to 40 ng/mL detects iron deficiency better, and women with hair loss have, on average, lower ferritin (Treister-Goltzman et al., 2022). Interpretation is always a medical matter, because ferritin rises with inflammation and infections and can look normal when it is not.

How to take the iron supplement

If the doctor prescribes oral iron, the way you take it makes a difference:

• Alternate days may be better. After a dose of iron, the body produces a hormone, hepcidin, which reduces absorption over the following 24 hours. In a study of women with iron-deficiency anaemia, absorption of a dose taken on alternate days was 40% to 50% greater than that of a dose taken the day after the previous one (Stoffel et al., 2020). The regimen should be set by the doctor.
• On an empty stomach or away from meals, if tolerated; with a glass of orange juice or a food rich in vitamin C.
• Away from coffee, tea, milk and calcium, which reduce absorption. Leave at least 2 hours in between.
• Common effects: dark stools (normal), constipation, nausea. If they are bothersome, talk to your doctor: changing the dose, the timing or the formulation usually solves it.
• Duration: haemoglobin improves within weeks, but replenishing reserves usually takes 3 months or more. Stopping too early is a common mistake: in a Spanish study, mothers took on average only half of the iron prescribed (Ruiz de Viñaspre-Hernández et al., 2021).

Intravenous iron

When anaemia is marked, oral iron is not tolerated or does not work, the doctor may prescribe intravenous iron, given in hospital or at a health centre. It replenishes reserves faster and is compatible with breastfeeding.

Iron in your diet

Diet helps to maintain reserves, but it is rarely enough to correct a deficiency that has already set in.

Other vitamins and minerals

Iodine: supplement recommended during breastfeeding

Iodine is essential for the mother's thyroid and for the development of the baby's brain, which receives it through milk. In Portugal, the Directorate-General of Health recommends a daily iodine supplement of 150 to 200 micrograms, as potassium iodide, from before conception, throughout pregnancy and during exclusive breastfeeding. In women with thyroid disease, the supplement may not be indicated and should be decided with the doctor.

Vitamin D

The deficiency is common in Portugal, especially in winter and in those who spend little time outdoors. Breast milk has little vitamin D, which is why paediatricians usually recommend supplementing the baby. For the mother, the need for a supplement is assessed case by case.

Vitamin B12

It is found almost only in foods of animal origin. Vegetarian and, above all, vegan mothers need a supplement, because the deficiency can pass to the baby through the milk and affect its development. Those who have had bariatric surgery or take metformin should also be monitored.

Folic acid

Essential before and in early pregnancy. After birth, a diet with green vegetables and pulses generally meets the needs. It can be continued if you are planning another pregnancy.

Omega 3 (DHA)

DHA passes into milk and is important for the baby's brain and vision. Two portions of oily fish a week, such as sardine, mackerel or salmon, are the simplest way to get it. Those who do not eat fish can discuss a supplement with their doctor.

Zinc and protein

Needs increase during breastfeeding. Meat, fish, eggs, dairy, pulses and seeds meet them in most cases. Protein is particularly important for hair, which is made of keratin.

Which tests make sense after birth

Not all mothers need blood tests. They make sense when there is marked tiredness, prolonged hair loss, a haemorrhage at birth or anaemia during pregnancy.

Thyroid: a point not to forget

Postpartum thyroiditis affects about 5% to 10% of women. It may start with an overactive thyroid phase between the 1st and 4th month after birth, with anxiety, insomnia and palpitations, and progress to an underactive thyroid between the 4th and 8th month, with tiredness, weight gain and low mood (American Thyroid Association). The symptoms are easily confused with those of the postpartum period, and hair loss may get worse.

Beware of biotin: if you take supplements containing biotin, stop them at least 1 day before the tests, or longer if the dose is high. Biotin can distort thyroid results (Fan et al., 2019).

More details in Blood tests for hair loss: what to ask for.

Supplements: what makes sense and what to avoid

It makes sense

• Iodine, during exclusive breastfeeding, as recommended by the DGS.
• Iron, when blood tests show a deficiency, at the dose and for the length of time indicated by the doctor.
• Vitamin B12, in vegetarian and vegan mothers.
• Vitamin D, when there is a deficiency or risk factors.
• Continue the prenatal multivitamin, if your doctor has recommended it for the postpartum period.

With care or to avoid

• "Hair, skin and nails" supplements. Many have high doses of biotin, vitamin A or selenium. Excess vitamin A and selenium can even cause hair loss, and biotin distorts test results (Almohanna et al., 2019; Fan et al., 2019).
• Iron "just in case" without blood tests. Without a deficiency, it brings no benefit and causes gastrointestinal effects.
• Adding up several supplements. It is easy to double up doses without realising. Bring all the packaging to the consultation.
• Teas and supplements "to increase milk". Some contain herbs without established safety in breastfeeding. Talk first to your doctor, nurse or breastfeeding counsellor.

A simple rule: blood tests first, then supplements.

A practical meal plan for the postpartum period

With a newborn, there is little time to cook. The aim is to have simple meals, prepared in advance or with help.

Tips for day to day

• Cook double and freeze portions: soups, pulse stews, meatballs.
• Keep snacks ready within reach during feeds: fruit, yoghurts, nuts, cheese.
• Combine vitamin C with plant-based iron: orange, kiwi, pepper, tomato.
• Keep coffee and tea away from main meals and from the iron supplement.
• Fish twice a week, preferably small oily fish; limit large predatory fish, such as swordfish and fresh tuna, because of mercury.
• Drink water throughout the day; a glass at each feed is a good guide.
• Accepting help: ask family or friends for ready-made meals instead of gifts.

When to seek a medical assessment

Seek urgent help if you have breathlessness at rest, chest pain, fainting, a very fast heartbeat or heavy vaginal bleeding.

Book a consultation if:

Persistent low mood, anxiety and a feeling of being unable to care for the baby deserve their own attention: talk to your GP or obstetrician.

At Luxmed, the Hair Medicine consultation assesses postpartum hair loss and, when indicated, requests the right tests to find out whether iron, thyroid or another deficiency lies behind it.

This article is for information only and does not replace follow-up with your doctor, obstetrician or paediatrician.

Frequently asked questions