Table 2.

Non-modifiable and modifiable risk factors for premature birth.

2a: Non-modifiable risk factors

High-risk

•Women who have delivered preterm before

•Women who are pregnant with greater than one baby (multiple gestation)

•Women with abnormalities of the reproductive system, particularly the cervix if it is short or shortens early in the second trimester (National Institutes for Health (NIH), 2017)

Lower risk

•Placenta previa where the placenta implants in the lowest part of the uterus and covers all or part of the opening to the cervix

•Rupture of the uterus is more likely with a previous caesarean delivery or removal of a uterine fibroid.

•Ethnicity with preterm labour and birth occurring more often among certain racial and ethnic groups.

•Mother's age with those younger than age 18 and those over age 35 more at risk

•Women who become pregnant through in vitro fertilization have an 80% higher risk for spontaneous preterm birth. This is unrelated to multiple gestation.

•Fetal abnormality

2b: Modifiable risk factors

•Infection/inflammation as a cause – includes urinary tract infections, dental health, sexually transmitted infections and vaginal infections, avoiding disease - Influenza vaccination

•Maternal disease processes including a pre-pregnancy type-2 diabetes, gestational diabetes and hypertension

•Life-style factors including obesity, smoking, drinking alcohol and use of illegal drugs

•Lack of antenatal care

•Work related stress with long working hours with long periods of standing

•Home related stress, lack of social support, domestic violence, including physical, sexual, or emotional abuse

•Exposure to certain environmental pollutants

•A short time period between pregnancies (less than 6 months between a birth and the beginning of the next pregnancy)