Hair loss during pregnancy is a concern that affects some women, often causing distress at an already demanding time. Whilst pregnancy is widely associated with thicker, fuller hair due to rising oestrogen levels, the reality is more nuanced — some women experience increased shedding, particularly in the first trimester or after delivery. Understanding why pregnancy-related hair loss occurs, when to seek medical advice, and which management options are safe for both mother and baby can help women navigate this experience with greater confidence and clarity.

Why Hair Loss Happens During Pregnancy

Hair loss during pregnancy is primarily driven by hormonal changes; whilst rising oestrogen usually thickens hair, some women experience shedding in the first trimester, and postpartum telogen effluvium — triggered by falling oestrogen after birth — is the most common and well-documented form.

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Hair loss during pregnancy can be an unexpected and distressing experience, particularly given the common belief that pregnancy leads to thicker, fuller hair. In reality, the relationship between pregnancy and hair health is more complex and varies considerably between individuals and trimesters.

Hair growth follows a cyclical pattern consisting of three phases: the anagen (growth) phase, the catagen (transitional) phase, and the telogen (resting/shedding) phase. Under normal circumstances, approximately 85–90% of hair follicles are in the active growth phase at any given time.^[6] During pregnancy, the significant rise in oestrogen typically prolongs the anagen phase, meaning many women experience thicker, fuller hair — particularly during the second and third trimesters. This is the basis for the well-known association between pregnancy and improved hair appearance.

However, some women do experience increased shedding, particularly in the first trimester, when the body is undergoing rapid hormonal adjustment. This is less common than the hair thickening many women notice, and clinically significant hair loss during pregnancy itself is less frequent than the hair loss that occurs after delivery.

Postpartum telogen effluvium — diffuse shedding triggered by the sharp fall in oestrogen after birth — is far more common and well-documented. It typically begins around 2–4 months after delivery, peaks at approximately 4 months, and in most cases resolves naturally by 6–12 months postpartum (NHS; British Association of Dermatologists).^[1][6] Understanding this physiology can help women feel reassured and better equipped to seek appropriate support when needed.

When to Speak to Your GP or Midwife

Seek GP or midwife advice if you notice sudden clumping hair loss, patchy bald areas, scalp inflammation, or hair loss accompanied by fatigue, weight changes, or cold intolerance, as these may indicate an underlying condition such as thyroid dysfunction or iron deficiency anaemia.

Whilst some degree of hair shedding during pregnancy may be within normal variation, there are specific circumstances in which it is important to seek professional advice promptly. Your GP or midwife can help determine whether the hair loss is a benign, hormonally driven change or a sign of an underlying condition requiring investigation or treatment.

You should contact your GP or midwife if you notice:

• Sudden or significant hair loss in large clumps

• Patchy bald areas on the scalp (which may suggest alopecia areata)^[2]

• Hair loss accompanied by fatigue, weight changes, cold intolerance, or mood disturbance (possible signs of thyroid dysfunction)

• Scalp irritation, redness, scaling, or tenderness

• Hair loss alongside other symptoms such as severe nausea, vomiting, or nutritional concerns

Initial investigations your GP may arrange include a full blood count (FBC), serum ferritin, and thyroid-stimulating hormone (TSH) — with free T4 if TSH is abnormal. Vitamin D may be checked if deficiency is suspected. Routine zinc or biotin testing is not recommended in the absence of specific clinical concern.

In the UK, routine antenatal care includes FBC at the booking appointment and again at 28 weeks (NICE NG201).^[3] Anaemia in pregnancy is defined as haemoglobin below 110 g/L in the first trimester or below 105 g/L in the second and third trimesters.^[3][5] A serum ferritin below 30 micrograms/L suggests iron deficiency even when haemoglobin appears normal (BSH guideline on iron deficiency in pregnancy and postpartum, 2021).^[5]

Thyroid disorders — both hypothyroidism and hyperthyroidism — are not uncommon in pregnancy and can present with hair thinning alongside other symptoms. NICE NG145 advises thyroid function testing where there is clinical suspicion, and trimester-specific reference ranges should be used when interpreting results.

If hair loss is severe, rapidly progressive, associated with scalp inflammation or pustules, or if there is concern about scarring alopecia, your GP should consider early referral to a dermatologist. You should also seek review if hair loss persists beyond 12 months postpartum or if you notice frontal or vertex thinning that may suggest androgenetic alopecia.

It is always better to raise concerns early rather than wait. Your midwife is an excellent first point of contact and can refer you appropriately. Hair loss can significantly affect wellbeing and mental health during an already demanding time, and this is a valid reason to seek support.

Common Causes and Contributing Factors

The most common causes of pregnancy-related hair loss include hormonal fluctuations, iron or ferritin deficiency, thyroid dysfunction, and nutritional depletion — often from a combination of factors rather than a single cause.

Hair loss during pregnancy is rarely attributable to a single cause. In most cases, it results from a combination of hormonal, nutritional, and physiological factors that interact throughout the course of pregnancy.

Hormonal changes are the most significant driver. Whilst rising oestrogen typically prolongs the growth phase during pregnancy, some women experience a temporary disruption to the hair cycle — particularly in the first trimester — that can result in increased shedding. After delivery, the rapid fall in oestrogen is the primary trigger for postpartum telogen effluvium: a diffuse, non-scarring form of hair loss in which a larger proportion of follicles simultaneously enter the resting and shedding phase (British Association of Dermatologists).

Nutritional deficiencies are another important contributing factor. Pregnancy places considerable demands on the body's nutrient stores, and the following have been associated with hair loss:

• Iron and ferritin — iron deficiency is one of the most common nutritional problems in pregnancy and is a well-established cause of diffuse hair thinning (BSH, 2021)^[5]

• Zinc — essential for hair follicle function; deficiency is uncommon in the UK but may occur in the context of poor diet or severe vomiting

• Biotin (vitamin B7) — true deficiency is rare; routine supplementation is not recommended unless there is a specific clinical indication

• Vitamin D — there is an association between low vitamin D and hair loss, though the evidence is largely observational and causation has not been established

Thyroid dysfunction is a well-established cause of diffuse hair thinning and should be excluded through appropriate blood tests (NICE NG145).^[4]

Hyperemesis gravidarum — severe pregnancy-related nausea and vomiting — can contribute to nutritional depletion and subsequent hair loss (RCOG Green-top Guideline on Hyperemesis Gravidarum).^[7]

Scalp conditions such as seborrhoeic dermatitis, psoriasis, or traction alopecia from tight hairstyles can also contribute to hair shedding and should be considered where scalp symptoms are present.

Psychological stress, which many women experience during pregnancy, is associated with telogen effluvium, likely through complex neuroendocrine pathways; however, the precise mechanism in humans is not fully established and this should be understood as an association rather than a proven causal relationship. Identifying and addressing contributing factors is key to effective management.

Safe Management Options During Pregnancy

Finasteride is contraindicated and topical minoxidil is not recommended during pregnancy; safe management focuses on optimising nutrition, treating underlying deficiencies under medical supervision, and gentle hair care practices.

Managing hair loss during pregnancy requires a careful, evidence-informed approach that prioritises the safety of both mother and baby. Many conventional hair loss treatments are not suitable during pregnancy:

• Finasteride is contraindicated in pregnancy due to the risk of harm to a male foetus (BNF; SmPC for finasteride). Women who are pregnant or may become pregnant should not handle crushed or broken finasteride tablets.

• Topical minoxidil is not recommended during pregnancy or breastfeeding. The UK Summary of Product Characteristics (SmPC) for topical minoxidil (e.g., Regaine for Women) advises that it should be avoided in these circumstances. It is not classified as an absolute contraindication in the same way as finasteride, but use should be discontinued before conception if possible and not started during pregnancy.

Safe and practical management strategies include:

• Optimising nutrition: Eating a well-balanced diet rich in iron, protein, and a variety of vitamins and minerals supports overall health during pregnancy. Lean meats, legumes, leafy green vegetables, eggs, and nuts are all beneficial choices.

• Pregnancy-safe supplementation: NHS guidance recommends folic acid 400 micrograms daily (until 12 weeks of pregnancy) and vitamin D 10 micrograms (400 IU) daily throughout pregnancy for all women.^[9] Iron supplementation should only be taken if advised by your GP or midwife following blood tests — routine iron in a multivitamin is not recommended for all pregnant women (NHS Vitamins, supplements and nutrition in pregnancy).^[9] Always consult your GP or midwife before taking additional supplements, as excessive doses of certain vitamins (for example, vitamin A) can be harmful in pregnancy. If you are taking high-dose biotin supplements, inform your healthcare professional before blood tests are taken, as biotin can interfere with a range of immunoassays — including thyroid function tests — and may affect results (MHRA Drug Safety Update).^[8]

• Treating underlying conditions: If blood tests reveal iron deficiency anaemia or thyroid dysfunction, treating these conditions appropriately under medical supervision can help reduce hair shedding.

• Gentle hair care: Avoiding excessive heat styling, tight hairstyles (which can cause traction alopecia), and harsh chemical treatments can minimise mechanical hair loss. Using a wide-toothed comb and a mild, sulphate-free shampoo is advisable.

• Psychological support: If hair loss is causing significant distress, speaking to your GP about referral for counselling or support through the perinatal mental health pathway may be beneficial.

For most women, hair loss during pregnancy — and particularly postpartum shedding — resolves naturally within 6–12 months without specific treatment (NHS).^[1][6] If shedding is severe, persists beyond 12 months after delivery, or is accompanied by a pattern of frontal or vertex thinning, please seek a further review with your GP.

If you experience a suspected side effect from any medicine used during pregnancy, you can report this to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk or through the Yellow Card app.

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