Risk Factors for Premature Birth

11.06.2024 | 3 min read

Nearly 1 in 10 women who give birth experience premature or preterm birth, defined as any birth before the 37th week of pregnancy. There are a variety of inherent health, environmental and lifestyle factors that increase the risk of premature birth. In some cases, labor may be induced early if there are health risks for the mother or baby. Other times, mothers may go into premature labor.

What are warning signs and symptoms before premature labor?

Premature births can happen without any known cause, but there are some signs and symptoms that suggest higher risk of premature labor. Signs of preterm labor include:

More than four contractions in an hour that are not relieved by changing positions or other relief measures
Vaginal bleeding
Cramping, similar to menstrual cramps
An increase or change of watery, mucus-like or bloody vaginal discharge
Pressure in the pelvic area, or feeling the baby push down
Backache, especially lower back pains
Preterm rupture of membranes, or water breaking

There are no definite warning signs of a premature birth that show up early in pregnancy. Get regular medical care during pregnancy to monitor your health and the health of the fetus and identify any potential risk factors for an early birth.

Health factors that increase risk of premature birth

Existing health factors can affect the risk of premature birth. Some are related to medical history, especially past pregnancies, and others are linked to existing conditions or factors. These include:

Having delivered preterm before
Being pregnant with two or more babies
Fewer than 6 months between pregnancies
Having had multiple previous pregnancies
Using assisted reproductive techniques, like in-vitro fertilization
Previously having had a Caesarean section (C-section) or having had uterine fibroids removed, which can increase the risk of uterine rupture
Having a short cervix or the shortening of the cervix during gestation
Placenta previa, in which the placenta covers the cervix completely or partially
Developmental anomalies in the fetus
Being underweight or obese prior to pregnancy
Malnutrition
Late or no health care during pregnancy
Ethnicity – African Americans, Native Americans and Alaska Native mothers are at higher risk of premature birth
Being under 18 or over 35 at the time of pregnancy
Urinary tract infections
Sexually transmitted diseases
Vaginal infections such as bacterial vaginosis or trichomoniasis
High blood pressure
Heart disease
Vaginal bleeding, spotting or bloody discharge
Diabetes
Blood clotting issues or anemia

Environmental factors that increase risk of premature birth

Environmental factors at home or work can affect the risk of premature birth. Increased stress from your environment can raise the risk of pre-term birth. Women who live in higher-polluted areas have a higher-risk of premature birth than other women. Other environmental factors include:

Domestic violence including physical, sexual or emotional abuse
Lack of social support
Stress
Long working hours with uninterrupted standing
Exposure to certain environmental pollutants including DDT or DDE

Lifestyle choices that increase risk of premature birth

Some lifestyle choices and substance use increase the risk of premature birth and developmental challenges for the baby. These lifestyle choices include:

Smoking
Drinking alcohol
Using illegal drugs
Eating a diet lacking in nutrients

How to reduce the risk of premature birth

Considering all the factors that contribute to an increased risk of premature birth, there are ways to reduce the risk as well. These include:

Before pregnancy:

Maintaining a healthy weight
Eating a well-balanced nutritious diet
Stop smoking and reduce alcohol consumption
Avoid illegal drug use
Waiting six months or longer between pregnancies

During pregnancy:

Seeing a doctor early in pregnancy and regularly throughout
Drinking plenty of fluids and maintaining good hydration
Eating a well-balanced nutritious diet
Managing chronic conditions such as diabetes, hypertension and autoimmune conditions
De-stressing and avoiding high stress situations