High-risk pregnancies

A pregnancy is considered high risk if one or more risk factors for adverse pregnancy outcomes are present at the outset or develop during the course of that pregnancy. Maternal factors that increase risk include age, preexisting conditions, and certain behaviors. Other factors related to the fetus, placenta, and conditions triggered or worsened by pregnancy also affect outcomes. Early identification and management of high-risk pregnancies is essential to prevent and treat associated maternal and fetal complications. Patients with identified conditions may require antepartum fetal surveillance, further diagnostics, preventative interventions, specialist referral, birth planning, and additional counseling related to peripartum care. Patients who seek care for the onset, exacerbation, or complication of a high-risk condition during pregnancy require urgent evaluation and specialized care. Acute management includes stabilization and resuscitation, fetal monitoring, urgent evaluation by maternal-fetal medicine specialists, identification and treatment of the underlying condition, and in some cases, emergency delivery.

See also “Prenatal care” and “Abnormal labor and delivery.”

General principles

• The impact of individual risk factors on maternal and fetal outcomes varies for each pregnancy.
• Factors can vary in severity, interact with other risk factors, and respond to preventive care and medical advances.
• The prognosis for each high-risk pregnancy is evaluated on an individual basis by a maternal-fetal medicine specialist.

Maternal factors ^[1][2][3][4]

• Advanced maternal age
• Preexisting medical conditions ^[5]
  • Metabolic: e.g., hypertension, pregestational diabetes mellitus, obesity
  • Cardiopulmonary: e.g., structural heart disease, asthma
  • Pulmonary hypertension: associated with major adverse cardiac events, hypertensive pregnancy disorders, preterm labor, and stillbirth ^[6]
  • Anemia: e.g., iron deficiency anemia, sickle-cell disease
  • Antiphospholipid syndrome: associated with pregnancy loss, preterm labor, hypertensive pregnancy disorders, placental abruption, and stillbirth ^[7]
  • Renal: e.g., chronic kidney disease
  • Other: e.g., HIV infection, myasthenia gravis, transplantations
• Preexisting gynecological conditions: e.g., uterine leiomyoma, history of uterine surgery
• Risk factors for hypertensive pregnancy disorders
• Substance use: e.g., tobacco, alcohol, stimulants, opioids

Pregnancy is associated with significant mortality in patients with pulmonary artery hypertension. ^[6][8]

Fetal-placental factors ^[2][3][4]

• Multiple gestation
  • Increases the likelihood and effect of several other risk factors for adverse pregnancy outcomes and pregnancy complications
  • See “Complications of multiple gestations” for details.
• Fetal structural or genetic abnormalities
• Placental abnormalities: e.g., placenta accreta, placenta previa, placental abruption
• Vasa previa
• Infection: e.g., Zika infection, chorioamnionitis, toxoplasmosis, cytomegalovirus ^[9][10]
• Abnormal amniotic fluid levels: e.g., oligohydramnios, polyhydramnios
• Twin-to-twin transfusion syndrome

Pregnancy-related factors ^[2][3][4]

• Hypertensive pregnancy disorders: e.g., gestational hypertension, preeclampsia
• Gestational diabetes mellitus: can cause fetal macrosomia, which increases the risk of obstructed labor and shoulder dystocia.
• Assisted reproductive technology (e.g., in vitro fertilization): can be associated with preterm labor, intrauterine growth restriction, antepartum hemorrhages, abnormal labor and delivery, stillbirth, and major congenital malformations. ^[11]
• Pregnancy-associated liver diseases
• Hyperemesis gravidarum
• Rhesus incompatibility
• Postterm pregnancy
• Prior complicated pregnancies, e.g.:
  • Stillbirth
  • Preterm birth, preterm premature rupture of membranes (PPROM), or infant with low birth weight
  • Previous infant with anatomic or genetic abnormalities
  • Cervical insufficiency

General principles

• High-risk pregnancies typically require closer monitoring and more comprehensive prenatal care.
• Care is frequently sought unexpectedly during a high-risk pregnancy, e.g., for exacerbations of coexisting conditions or complications of pregnancy. ^[12][13]
• Individuals with high-risk conditions, intensive prenatal care requirements, or limited access to adequate prenatal care are more likely to present to emergency departments. ^[13][14]

Prenatal care ^[2][3][4]

• Refer patients with high-risk pregnancies to specialists as indicated, e.g.:
  • Maternal-fetal medicine
  • Pediatric specialists
• Consider increased monitoring of maternal and fetal well-being with:
  • Clinical evaluation
  • Antepartum fetal surveillance
  • Prenatal ultrasound
• Discuss the potential impacts of high-risk pregnancy with patients on:
  • Mode and timing of delivery
  • Need for postpartum and neonatal monitoring after birth
• For more information, see “Prenatal care” and “Pregnancy complications.”

Approach to emergencies ^[5][15]

• ABCDE survey: Obtain IV access and consider cardiac monitoring and supplemental O₂.
• Assess gestational age.
• Consider the risk-benefit of imaging using ionizing radiation.
• Consider electronic fetal heart rate monitoring, if indicated.
• Identify and treat exacerbations or complications of medical conditions following pregnancy-specific considerations (see “Condition-specific management”).
• Follow any existing care plans.
• Urgently consult maternal-fetal medicine, whenever available.
• Consult treating specialists for medical conditions (e.g., pulmonology, neurology, cardiology) as needed.

Minimize fetal radiation exposure whenever possible, but do not avoid necessary imaging due to radiation concerns, as this can lead to worse fetal outcomes. ^[16]

Active labor

• Urgently consult OBGYN; assisted vaginal delivery or emergency cesarean delivery may be required.
• Perform emergency preoperative evaluation.
• Monitor for fetal distress using cardiotocography.
• If specialist-performed vaginal or cesarean delivery is delayed:
  • Perform manually assisted vaginal delivery.
  • Provide intrauterine resuscitation, if necessary.
  • Treat obstructed labor, if present.
  • Consult neonatology and prepare equipment for neonatal resuscitation after delivery.
  • Monitor for peripartum complications: e.g., postpartum hemorrhage, amniotic fluid embolism, eclampsia, puerperal sepsis.

Condition-specific management

Disposition

• Evaluate disposition on an individual basis using shared decision-making and in consultation with a specialist (i.e., maternal-fetal medicine or OBGYN) whenever possible.
• Due to their severity, the following conditions usually require hospital admission; ICU admission and/or operative intervention may also be required:
  • Antepartum hemorrhage
  • Preeclampsia, eclampsia, and HELLP syndrome
  • Active labor and its complications (e.g., birth asphyxia, postpartum hemorrhage)
  • Preterm labor
  • Acute fatty liver of pregnancy
  • Hyperemesis gravidarum
  • Pulmonary hypertension ^[6]
  • Moderate- and high-risk cardiac conditions (e.g., pulmonary hypertension, moderate or severe valvular heart disease) ^[6][18]
• NICU admission may be required for neonates with prematurity or birth complications.