What are the characteristics of mild, moderate, and strong contractions in a high-risk pregnant woman with a history of obstetric complications and underlying medical conditions, such as preeclampsia or fetal growth restriction?

Characteristics of Uterine Contractions: Mild, Moderate, and Strong

Braxton-Hicks contractions are irregular, subside with rest, and are uncomfortable but not painful, whereas true labor contractions are regular, painful, and do not resolve with rest—this distinction is critical for determining whether to cease activity and seek immediate medical evaluation. 1, 2

Distinguishing Braxton-Hicks from True Labor Contractions

Braxton-Hicks Contractions (Physiologic)

• Timing pattern: Irregular intervals with no consistent pattern 1, 2
• Pain quality: Generally uncomfortable but not painful; described as tightening or pressure sensation 1, 2
• Response to rest: Subside completely when the woman stops activity and rests 1, 2
• Frequency with activity: May become more intense or frequent with moderate-to-vigorous physical activity, especially in the third trimester 1, 2
• Clinical significance: Benign physiologic phenomenon that does not indicate preterm labor 1, 2

True Labor Contractions (Pathologic When Preterm)

• Timing pattern: Regular intervals that become progressively closer together 1, 2
• Pain quality: Painful contractions that increase in intensity over time 1, 2
• Response to rest: Do not subside with rest or cessation of activity 1, 2
• Clinical significance: May indicate active preterm labor requiring immediate medical evaluation 1, 2

Critical Action Points

Any pregnant woman experiencing regular and painful uterine contractions must immediately cease all activity and seek advice from a healthcare provider, as this pattern distinguishes preterm labor from benign Braxton-Hicks contractions. 1, 2

Special Considerations in High-Risk Pregnancies

Preeclampsia Without Fetal Growth Restriction

• Mild preeclampsia: Women may experience Braxton-Hicks contractions during light physical activity (walking, bodyweight exercises, stretching) without adverse effects on blood pressure, uterine contractions, vaginal bleeding, uterine blood flow, or fetal heart rate 1
• Severe preeclampsia: Should not engage in strenuous physical activity but may maintain activities of daily living 1, 2
• Monitoring requirement: Any uterine contractions in severe preeclampsia warrant immediate evaluation, as these women require delivery and should avoid activities that stimulate contractions 1, 2

Preeclampsia With Fetal Growth Restriction

• Severe disease indicator: The combination of preeclampsia and fetal growth restriction (estimated fetal weight <10th percentile) represents severe preeclampsia with significantly worse maternal and perinatal outcomes 1, 3, 4, 5
• Exercise response: Transient adverse responses to physical activity occur, including reduction in placental blood flow, increased umbilical artery resistance, and decreased fetal well-being 1
• Contraction management: Any uterine activity should prompt immediate cessation of activity and medical evaluation, as placental dysfunction makes the fetus particularly vulnerable 1, 4, 5
• Maternal complications: Severe hypertension and critical maternal complications occur significantly more frequently than in preeclampsia without fetal growth restriction 5

Fetal Growth Restriction Alone

• Contraction response: Acute exercise in women with fetal growth restriction (estimated fetal weight <5th percentile) causes transient increases in umbilical artery pulsatility index, fetal bradycardia, and absent end-diastolic flow 1
• Activity restriction: Women should avoid moderate-to-vigorous physical activity but maintain activities of daily living 1
• Risk of preeclampsia development: Approximately 15% of women diagnosed with fetal growth restriction develop preeclampsia later, particularly those with early-onset fetal growth restriction and proteinuria at entry 5

Cervical Insufficiency

• Contraction avoidance: Women should maintain only activities of daily living and avoid any moderate-to-vigorous physical activity that could stimulate contractions 1, 2
• Cerclage presence: These recommendations apply whether or not a prophylactic or rescue cervical cerclage is in place 1

Common Pitfalls to Avoid

Do not dismiss regular contractions as "just Braxton-Hicks" in high-risk women—the presence of preeclampsia, fetal growth restriction, or cervical insufficiency fundamentally changes the risk profile and requires immediate evaluation of any regular uterine activity. 1, 2, 5

• Gestational age matters critically: In severe preeclampsia before 24 weeks, perinatal survival is essentially zero, and before 26 weeks with concurrent severe fetal growth restriction, expectant management is not recommended due to extremely low perinatal survival rates (0-30%) despite high maternal morbidity (43%) 4
• Early-onset fetal growth restriction with proteinuria: This combination represents a particularly high-risk group for subsequent preeclampsia development, with diagnosis of fetal growth restriction occurring around 28.8 weeks, preeclampsia developing at 32.6 weeks, and delivery required by 33.3 weeks 5
• Cardiac dysfunction indicator: Both preeclampsia and fetal growth restriction cause similar patterns of fetal cardiac remodeling and dysfunction, with elevated cord blood B-type natriuretic peptide levels indicating myocardial stress 6