Preterm Birth Management

Risk Factors and Screening

Women at risk of preterm birth should be screened for cervical length, with a midtrimester cervical length of ≤25 mm being diagnostic of a short cervix, according to the American College of Obstetricians and Gynecologists (ACOG) 1
The strongest predictor of preterm birth is a previous spontaneous preterm birth, and other risk factors include short cervical length on ultrasound, multiple gestation, uterine anomalies, cervical procedures, bacterial vaginosis, and periodontal disease, as stated by ACOG 1
Transvaginal ultrasound is the recommended approach for cervical length measurement, with measurements following standardized procedures as described by organizations such as the Perinatal Quality Foundation or the Fetal Medicine Foundation, according to ACOG 1

Vaginal progesterone is recommended for women with a cervical length ≤20 mm diagnosed before 24 weeks, with consideration for vaginal progesterone for cervical length 21-25 mm based on shared decision-making, as recommended by ACOG 1
17-alpha hydroxyprogesterone caproate should not be used for short cervix, including compounded formulations, according to ACOG 1
Cerclage is not recommended for short cervix (10-25 mm) without cervical dilation in women without a history of preterm birth, as stated by ACOG 1
Cervical pessary is not recommended for prevention of preterm birth, according to ACOG 1

Home uterine activity monitoring (HUAM) is not recommended as it has been shown to be ineffective in preventing preterm birth, according to the American Academy of Family Physicians (AAFP) 2
Salivary estriol testing is not recommended due to high false-positive rates and lack of established usefulness, as stated by AAFP 2
Activity restriction (bed rest) should not be routinely prescribed as evidence suggests it may actually increase the risk of preterm birth, according to ACOG 3

Antenatal corticosteroids should be given to improve fetal lung maturity if delivery is anticipated before 35 weeks' gestation, as recommended by the American Association for the Study of Liver Diseases (AASLD) 4
For women with preeclampsia/HELLP syndrome at risk of preterm delivery, low-dose aspirin (100-150 mg) daily from week 12 to weeks 36-37 may be prescribed for prevention, according to AASLD 4
Calcium supplementation (≥1 g/day) may reduce risk, particularly for women with low calcium diet, as stated by AASLD 4
Antihypertensive treatment should aim to keep SBP <160 mmHg and DBP <110 mmHg, according to the European Society of Cardiology (ESC) 5
Magnesium sulfate may be used for seizure prevention and neuroprotection if delivery is required before 32 weeks, as recommended by AASLD 4

Women at high risk of imminent preterm birth should be transferred to facilities with appropriate neonatal intensive care capabilities, as recommended by AAFP 2
Tocolysis options include nifedipine, beta-mimetics, magnesium sulfate, and NSAIDs, although the choice of tocolytic agent may depend on individual patient factors and clinical judgment, according to ACOG 1

Reduce weight limits when lifting objects far from the body, performing repetitive lifts, lifting for extended periods, or lifting from floor level or overhead, with a maximum Recommended Weight Limit (RWL) of 51 pounds for an ideal lift, as recommended by the National Institute for Occupational Safety and Health (NIOSH) 6
Keep objects within 15 inches of body before 20 weeks of gestation, and within 20 inches of body after 20 weeks of gestation due to abdominal protrusion, and avoid floor-level lifting and overhead lifting completely during pregnancy, according to NIOSH 6
Reduce weight limits for all lifting patterns during pregnancy, and avoid routine activity restriction, as evidence suggests it may actually increase the risk of preterm delivery, according to ACOG 3
Modest activity restriction (4-6 hours rest per day) may reduce preeclampsia risk, but the evidence quality is low, with limited strength of evidence, and complete activity restriction may increase complications in pregnant women, according to ACOG 3

Begin with low-intensity resistance training, as recommended by the American Heart Association (AHA), and patients with stable cardiovascular disease can participate in low to moderate-intensity resistance training without additional testing if they have acceptable functional capacity (≥4 METs), according to the American College of Cardiology (ACC) 7
Use machines rather than free weights for greater safety, as suggested by AHA, and machine-based lifting is safer than free weights for those with advanced arthritis, severe osteoporosis, neuropathies, or neurological conditions, according to ACC 7