Preterm birth 2025: causes, warning signs and modern care

Author photo
Zappelphilipp Marx•
Preterm baby in an incubator on a neonatal unit

Worldwide, around one in ten babies is born before 37 weeks' gestation. Preterm birth is therefore a leading cause of childhood illness and mortality. This guide explains in plain language what preterm birth is, which warning signs should be taken seriously and how modern medicine protects preterm infants today.

What is preterm birth?

A birth is considered preterm when a baby is born before the completion of 37 weeks' gestation. Professional bodies distinguish several categories because prognosis and care differ substantially.

CategoryGestational ageTypical features
Extremely pretermbefore 28 weeks' gestationImmaturity of all organs, often requiring ventilation and intensive monitoring.
Very preterm28 to 31 weeks' gestationCare in a specialised neonatal unit; increased risk of brain and respiratory problems.
Moderate and late preterm32 to 36 weeks' gestationOften only short observation, but more frequent feeding difficulties, low blood sugar and neonatal jaundice.

In general: the earlier a baby is born, the more intensive the hospital care and the greater the importance of structured follow-up after discharge.

Causes and risk factors – why babies are born early

Preterm birth rarely has a single cause. Usually multiple factors interact, and in some cases the trigger remains unclear. Important known risk factors include:

  • Infections: for example bacterial vaginosis, urinary tract infections or untreated gum disease.
  • Multiple pregnancy and assisted reproduction: twins or triplets, particularly after IVF or ICSI, carry a substantially higher risk of preterm birth.
  • Cervical insufficiency: a cervix that is too short or opens prematurely, for example after a cone biopsy.
  • Placental problems: placental insufficiency, placental abruption or a low‑lying placenta.
  • Maternal pre-existing conditions: chronic high blood pressure, pre-eclampsia, diabetes, autoimmune or kidney disease.
  • Lifestyle: smoking, alcohol or drug use, significant underweight or overweight, and poor nutrition.
  • Social and psychological factors: high stress, domestic violence, financial worries or limited social support.

Detailed recommendations for assessing these risk constellations can be found, for example, in national guidelines on prevention and management of preterm birth.

Warning signs of impending preterm birth

Not every contraction is dangerous. However, there are symptoms that should always be promptly evaluated in a clinic or by a healthcare professional:

  • Regular, painful contractions before 37 weeks' gestation.
  • Suspected loss of amniotic fluid or premature rupture of membranes.
  • Vaginal bleeding, brownish or foul-smelling discharge.
  • Strong pressure downwards or the sensation that the baby is "dropping".
  • Marked shortening of the cervix on ultrasound.

In addition, tests such as detection of fetal fibronectin or certain inflammatory markers are used. They help to estimate the risk of birth in the coming days but never replace clinical assessment.

Preventing preterm birth – prevention 2025

Prevention ideally begins before a planned pregnancy and continues throughout pregnancy. Key elements include:

  • Optimal preparation: good control of chronic conditions, smoking cessation and counselling on medication before conception.
  • Regular antenatal care: consistent attendance at check-ups, including ultrasound assessment of the cervix in risk situations.
  • Progesterone for a short cervix: vaginal progesterone can reduce the risk of preterm birth in singleton pregnancies with a shortened cervix.
  • Cerclage or cervical pessary: for marked cervical insufficiency or recurrent late miscarriages, cerclage or silicone pessaries can mechanically support the cervix.
  • Infection screening and treatment: prompt treatment of urinary tract infections, bacterial vaginosis or other infections lowers the risk of complications.
  • Healthy lifestyle: balanced nutrition, exercise within recommended limits, adequate sleep and stress reduction support a stable pregnancy.

Many hospitals offer specialised clinics for high-risk pregnancies. There, individual preterm birth risks can be discussed and a tailored plan developed.

Acute management of threatened preterm birth

If preterm labour, bleeding or rupture of membranes occurs, this is an emergency situation that should always be assessed in a hospital. Further management is individualised and may include:

  • Monitoring of mother and baby: CTG, ultrasound, laboratory tests and swabs for infection diagnostics.
  • Tocolysis: tocolytic drugs such as atosiban or calcium channel blockers can often delay birth by a few days.
  • Antenatal corticosteroids: betamethasone or dexamethasone accelerate lung and organ maturation, particularly between about 24 and 34 weeks' gestation.
  • Magnesium sulphate for neuroprotection: in very preterm births magnesium sulphate may reduce the risk of severe brain injury.
  • Transfer to a perinatal centre: where possible, the pregnant person is transferred antenatally to a centre with highly specialised neonatal care.

Guidance is provided by, among others, the WHO on antenatal corticosteroids as well as national professional guidelines.

Modern neonatology and the role of parents

Perinatal centres combine high‑tech medicine with developmentally supportive care. This includes:

  • Gentle ventilation strategies using the lowest possible pressures to protect the lungs.
  • Modern incubators with stable temperature and noise control.
  • Consistent promotion of breastmilk, including human milk banks and individualised nutrient fortification.
  • Strict hygiene standards and infection prevention.

At the same time, parent–infant bonding is central. Kangaroo care (skin-to-skin contact), early involvement of parents in care tasks and psychological support help families manage the intensive period on the unit and promote the child's development.

Long-term outcomes and structured follow-up

Many moderately or late preterm children reach normal school and working life with good support. However, certain health issues are more common in preterm children:

  • Fine and gross motor developmental delays.
  • Visual and hearing impairments that require regular screening.
  • Chronic respiratory conditions such as bronchopulmonary dysplasia or asthma.
  • Attention and learning difficulties, sometimes accompanied by emotional challenges.

Many children benefit from interdisciplinary early intervention, for example via paediatric outpatient clinics, physiotherapy, occupational therapy or speech and language therapy. It is important that parents remain alert to concerns, raise them and seek support when needed.

Research and future prospects

Research teams worldwide are working on new ways to better predict preterm birth risk and to care for preterm infants more safely:

  • Biomarkers and immune profiles: blood tests may help to identify individual preterm birth risks early.
  • Microbiome approaches: studies are investigating whether certain probiotics can reduce the risk of severe intestinal disease such as NEC.
  • 'Artificial womb': experimental systems aim to give extremely preterm infants additional maturation time outside the uterus.
  • Digital support: apps and telemedicine can help monitor high‑risk pregnancies more closely and detect warning signs early.

Support for parents of preterm infants

In addition to medical care, parents of preterm infants mainly need reliable information and psychosocial support. Organisations such as the European Foundation for the Care of Newborn Infants (EFCNI) provide information materials, checklists and points of contact for families. Many hospitals also work with preterm support groups, breastfeeding support, psychological services and paediatric outpatient centres to help ensure a smooth transition home.

Conclusion

Preterm births cannot be completely prevented. However, knowing the main risk factors, taking warning signs seriously and ensuring guideline-based care in an experienced perinatal centre improves the chances of a stable start to life. Good follow-up and appropriate support help preterm infants and their families to take this unique journey step by step.

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Frequently Asked Questions (FAQ)

Estimates indicate that about one in ten births worldwide is preterm. Rates vary by country; in the UK the preterm birth rate is generally somewhat lower than the global average and varies by region and year.

A markedly shortened cervix on ultrasound is one of the most important measurable risk factors for preterm birth. The shorter the cervix and the earlier the cervix dilates, the higher the likelihood of a premature birth.

In certain situations, such as a singleton pregnancy with a shortened cervix, vaginal progesterone can reduce the risk of preterm birth. Whether treatment is appropriate is decided by the treating clinician based on the overall situation.

A cerclage or cervical pessary is primarily considered for marked cervical insufficiency or recurrent late miscarriages. The aim is to mechanically support the cervix to prevent or delay premature opening.

Tocolytics are drugs that can slow down or temporarily stop premature labour. They usually prolong the pregnancy by a few days to allow time for corticosteroid injections and possible transfer to a specialised centre.

Antenatal corticosteroid injections support maturation of the baby's lungs and other organs. They have been shown to reduce the risk of severe respiratory problems and improve survival when very early birth cannot be prevented.

Modern neonatal units use as gentle methods as possible, for example respiratory support with nCPAP or high-flow oxygen and ventilation with low peak pressures to protect the vulnerable lungs of preterm infants.

In kangaroo care, preterm infants lie skin-to-skin on a parent's chest. This helps to stabilise breathing, temperature and heart rate, strengthens bonding and often supports breastfeeding and parental wellbeing.

A negative fetal fibronectin test makes imminent birth in the next few days unlikely. This can help avoid unnecessary hospital admissions and focus monitoring, but it never replaces clinical judgement.

Preterm infants are somewhat more likely to have difficulties with motor skills, breathing, vision, hearing or attention. With regular checks and early intervention, many children can largely overcome these early disadvantages and lead normal lives.

Research projects are investigating blood tests that measure specific inflammatory and immune signals. They aim to indicate preterm birth risk early but are not yet established as routine tests in clinical practice.

The composition of gut bacteria appears to influence the risk of intestinal conditions such as NEC. Early studies suggest targeted probiotics may be protective, but definitive recommendations are not yet available.