From the Guidelines
High-risk obstetrics is defined as a pregnancy in which the woman, fetus, or infant is at risk of death or residual injury and requires additional resources, procedures, or specialized care to optimize outcomes, as stated in the 2021 study by the Society for Maternal-Fetal Medicine 1. The criteria for high-risk OB include various factors, such as:
- Maternal factors: advanced maternal age (over 35), pre-existing medical conditions (diabetes, hypertension, heart disease, autoimmune disorders, kidney disease, or obesity), and history of pregnancy complications (previous preterm birth, stillbirth, or cesarean delivery) 1, 2
- Pregnancy-specific conditions: gestational diabetes, preeclampsia, multiple gestation (twins or more), placental abnormalities (placenta previa or placenta accreta), and fetal growth restriction 1, 2
- Lifestyle factors: substance use (tobacco, alcohol, or drugs) and inadequate prenatal care 2
- Fetal concerns: congenital anomalies detected on ultrasound, abnormal genetic screening results, or abnormal amniotic fluid levels 2 These pregnancies require specialized care with more frequent monitoring, additional testing, and sometimes consultation with maternal-fetal medicine specialists, as outlined in the 2021 study by the Society for Maternal-Fetal Medicine 1. The American College of Obstetricians and Gynecologists (ACOG) also provides guidelines for levels of maternal care, which include basic care (level I), specialty care (level II), subspecialty care (level III), and regional perinatal health care centers (level IV) 3. The key to managing high-risk pregnancies is early identification of risk factors and provision of specialized care to optimize outcomes for both mother and baby, as emphasized in the 2021 study by the Society for Maternal-Fetal Medicine 1.
From the Research
High-Risk OB Criteria
The criteria for high-risk obstetrics (OB) include a history of preeclampsia, intrauterine growth restriction, fetal demise, or miscarriage, as well as being at high risk after first-trimester screening of preeclampsia 4. Other factors that may contribute to a high-risk pregnancy include:
- Chronic hypertension 5
- Pregestational insulin-treated diabetes mellitus 6
- Multiple gestations 6
- History of preeclampsia in a previous pregnancy 6
Prevention and Treatment
Preventive treatment of preeclampsia consists essentially of low-dose aspirin, which has been shown to decrease the risk of recurrence of preeclampsia by 10 to 15% 7. Low-molecular-weight heparin has also been associated with a significant reduction in the risk of preeclampsia and other placenta-mediated complications in high-risk women 4. The efficacy of low-dose aspirin may differ by ethnicity and race, with non-Hispanic white women appearing to benefit more from aspirin prophylaxis than Hispanic or non-Hispanic black women 6.
Key Findings
Key findings from the studies include:
- Low-dose aspirin reduces the risk of preeclampsia by 10 to 15% 7
- Low-molecular-weight heparin reduces the risk of preeclampsia and other placenta-mediated complications in high-risk women 4
- The efficacy of low-dose aspirin may differ by ethnicity and race 6
- Chronic hypertension is associated with an increased risk of vascular disease, including superimposed preeclampsia, intrauterine growth retardation, placental abruption, and preterm delivery 5