What is preterm birth?
Preterm birth is defined as delivery before 37 weeks of pregnancy have been completed. Generally, preterm birth can be categorized into three subtypes:
- extremely preterm (before 28 weeks)
- very preterm (28 to 32 weeks)
- moderate to late preterm (32 to 37 weeks)
According to the World Health Organization, the rate of preterm birth ranges from 5% to 18% of babies born across the globe. A medical report published by The Chinese University of Hong Kong in 2014 shows that the preterm birth rate in Hong Kong stands at 6.5% in recent years.
Preterm birth is the leading cause of death in newborns, and the second major reason for death in children under the age of 5 after pneumonia. Causes of prematurity remain unknown, but the following risk factors may increase the chance of preterm birth:
- History of miscarriage or preterm delivery
- Uterine abnormalities (e.g. cervical incompetence)
- Teenage mothers or women with advanced maternal age
- Placenta praevia or premature separation of placenta
- Hydramnios or oligohydramnios
- Smoking or alcohol abuse by mother
- Premature rupture of membranes
- Pre-eclampsia of the mother, multiple pregnancy, congenital abnormalities, etc.