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Preterm birth

Fact sheet N°363
Updated November 2013


Key facts

  • Every year, an estimated 15 million babies are born preterm (before 37 completed weeks of gestation), and this number is rising.
  • Over 1 million babies die annually from preterm birth complications.
  • Preterm birth is the leading cause of newborn deaths (babies in the first four weeks of life) and the second leading cause of death after pneumonia in children under five years.
  • Three-quarters of them could be saved with current, cost-effective interventions, even without intensive care facilities.
  • Across 184 countries, the rate of preterm birth ranges from 5% to 18% of babies born.

Overview

Preterm is defined as babies born alive before 37 weeks of pregnancy are completed. There are sub-categories of preterm birth, based on gestational age:

  • extremely preterm (<28 weeks)
  • very preterm (28 to <32 weeks)
  • moderate to late preterm (32 to <37 weeks).

Induction or caesarean birth should not be planned before 39 completed weeks unless medically indicated.

The problem

An estimated 15 million babies are born too soon every year. That is more than one in 10 babies. Around 1 million children die each year due to complications of preterm birth. Many survivors face a lifetime of disability, including learning disabilities and visual and hearing problems.

In almost all countries with reliable data, preterm birth rates are increasing. Globally, prematurity is the leading cause of newborn deaths (babies in the first four weeks of life) and the second leading cause of death after pneumonia in children under the age of five.

Inequalities in survival rates around the world are stark. In low-income settings, half of the babies born at 32 weeks (two months early) die due to a lack of feasible, cost-effective care, such as warmth, breastfeeding support, and basic care for infections and breathing difficulties. In high-income countries, almost all of these babies survive.

The solution

More than three-quarters of premature babies can be saved with feasible, cost-effective care – e.g. antenatal steroid injections (given to pregnant women at risk of preterm labour to strengthen the babies’ lungs), kangaroo mother care (the baby is carried by the mother with skin-to-skin contact and frequent breastfeeding) and antibiotics to treat newborn infections – even without the availability of neonatal intensive care.

To reduce preterm birth rates, women – especially adolescents – need better access to family planning and increased empowerment, as well as improved care before, between and during pregnancies.

Why does preterm birth happen?

Preterm birth occurs for a variety of reasons. Most preterm births happen spontaneously, but some are due to early induction of labour or caesarean birth, whether for medical or non-medical reasons.

Common causes of preterm birth include multiple pregnancies, infections and chronic conditions, such as diabetes and high blood pressure; however, often no cause is identified. There is also a genetic influence. Better understanding of the causes and mechanisms will advance the development of solutions to prevent preterm birth.

Where and when does preterm birth happen?

Over 60% of preterm births occur in Africa and South Asia, but preterm birth is truly a global problem. In the lower-income countries, on average, 12% of babies are born too soon compared with 9% in higher-income countries. Within countries, poorer families are at higher risk.

The 10 countries with the greatest number of preterm births1:

  • India: 3 519 100
  • China: 1 172 300
  • Nigeria: 773 600
  • Pakistan: 748 100
  • Indonesia: 675 700
  • The United States of America: 517 400
  • Bangladesh: 424 100
  • The Philippines: 348 900
  • The Democratic Republic of the Congo: 341 400
  • Brazil: 279 300

The 10 countries with the highest rates of preterm birth per 100 live births:

  • Malawi: 18.1 per 100
  • Comoros: 16.7
  • Congo: 16.7
  • Zimbabwe: 16.6
  • Equatorial Guinea: 16.5
  • Mozambique: 16.4
  • Gabon: 16.3
  • Pakistan: 15.8
  • Indonesia: 15.5
  • Mauritania: 15.4

Of 65 countries with reliable trend data, all but three show an increase in preterm birth rates over the past 20 years. Possible reasons for this include better measurement, increases in maternal age and underlying maternal health problems such as diabetes and high blood pressure, greater use of infertility treatments leading to increased rates of multiple pregnancies, and changes in obstetric practices such as more caesarean births before term.

There is a dramatic difference in survival of premature babies depending on where they are born. For example, over 90% of extremely preterm babies (<28 weeks) born in low-income countries die within the first few days of life; yet less than 10% of babies of this gestation die in high-income settings.

WHO response

In May 2012, WHO and partners – The Partnership for Maternal, Newborn & Child Health, Save the Children and the March of Dimes – published a report Born too soon: the global action report on preterm birth that included the first-ever estimates of preterm birth by country.

Born too soon is the latest contribution to the UN Secretary-General’s Global Strategy for Women’s and Children’s Health, which aims to save 16 million lives by 2015.

WHO is committed to reducing the health problems and lives lost as a result of preterm birth with the following specific actions:

  • to work with Member States and partners to develop an Every Newborn: An Action Plan to End Preventable Deaths under the umbrella of the UN Secretary-General’s Global Strategy for Women’s and Children’s Health;
  • to work with Member States to strengthen the availability and quality of data on preterm births;
  • to provide updated analyses of global preterm birth levels and trends every three to five years;
  • to work with partners around the world to conduct research into the causes of preterm birth, and test effectiveness and delivery approaches for interventions to prevent preterm birth and treat babies that are born preterm;
  • to regularly update clinical guidelines for the management of pregnancy and mothers with preterm labour or at risk of preterm birth, and those on the care of preterm babies, including kangaroo mother care, feeding babies with low birth weight, treating infections and respiratory problems, and home-based follow-up care; and
  • to develop tools to improve health workers’ skills and assess the quality of care provided to preterm babies.

1 Blencowe H, Cousens S, Oestergaard M, Chou D, Moller AB, Narwal R, Adler A, Garcia CV, Rohde S, Say L, Lawn JE. National, regional and worldwide estimates of preterm birth. The Lancet, June 2012. 9;379(9832):2162-72. Estimates from 2010.

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