Causes and risk factors

Around 1 in 4 premature infants are delivered early for medical reasons, either for their own or their mother’s safety.⁶ This can include a planned caesarean section carried out because of conditions such as severe pre-eclampsia (a disorder where a pregnant woman develops hypertension and produces urine with a high protein content) or due to an issue with the infant’s development. Other causes of early labour include emergency events such as infection or placental abruption.⁶

It is not always known why premature birth has occurred. However, several potential risk factors have been identified that can increase the likelihood that an infant will be born before 37 weeks:⁷

• If a woman has a history of spontaneous preterm delivery
• Women who are pregnant with twins or triplets
• Smoking, drinking alcohol and using illicit drugs during pregnancy
• Chronic conditions such as hypertension or diabetes
• If a woman is underweight, overweight or obese at the time of conception
• Maternal ill-health and infections.