What are the management strategies for a high-risk pregnancy with abnormal presentations, such as breech or transverse lie, in women with a history of previous complications or underlying medical conditions like hypertension or diabetes?

Abnormal Presentations in Pregnancy and High-Risk Management

Definition and Clinical Significance

Abnormal fetal presentations—including breech, transverse lie, face, brow, and compound presentations—are major contributors to cesarean delivery rates and define pregnancies as high-risk due to increased perinatal morbidity and mortality that is approximately three times higher than vertex presentations. 1

• Breech presentation is the most common malpresentation, occurring in 3-4% of singleton pregnancies at term 1
• Abnormal presentation detected at 28-30 weeks carries a 22.2% risk of persisting to term, while cephalic presentation at this gestational age has only a 0.75% risk of converting to abnormal presentation 2
• High-risk pregnancy is defined as any condition where the woman, fetus, or infant faces increased risk of death or residual injury requiring additional resources or specialized care 3, 4

Risk Factors for Abnormal Presentation

Key risk factors include multiparity, previous affected pregnancy, polyhydramnios, and fetal or uterine anomalies. 5

Additional high-risk factors that compound the presentation issue include:

• Cardiovascular disease (rheumatic heart valve disease, Marfan syndrome, Ehlers-Danlos syndrome) 3, 4
• Hypertensive disorders (chronic hypertension, preeclampsia) 3, 4
• Diabetes mellitus (pregestational and gestational) 3, 4
• Previous adverse pregnancy outcomes 3
• Multiple gestation 3
• Substance use and socioeconomic factors 3

Management Algorithm for Abnormal Presentations

External Cephalic Version (ECV)

ECV after 36 weeks is the primary intervention to convert breech or transverse lie to cephalic presentation, with a 45% success rate and 80% subsequent vaginal delivery rate when successful. 6

Success factors for ECV:

• Multiparity (trend toward better outcomes) 6
• Flexed breech presentation 6
• Transverse lie 6
• Posteriorly-located placenta 6
• Higher fetal birth weight (significantly associated with success) 6

ECV is safe with no significant fetal or maternal morbidity when performed by practitioners even with limited prior experience. 6

Criteria for Vaginal Breech Delivery

Vaginal delivery may be as safe as cesarean section for carefully selected term breech presentations when ALL of the following criteria are met: 1

• Frank breech presentation only 1
• Estimated fetal weight 2500-3500 grams 1
• Adequate pelvimetry without hyperextended fetal head 1
• Normal labor progression 1
• No evidence of fetal hypoxia with continuous monitoring 1
• Maternal weight under 90 kg 1

If any criterion is not fulfilled or continuous fetal monitoring cannot be performed, cesarean section is advisable. 1

Cesarean Delivery Indications

Cesarean delivery should be considered for obstetric indications or specific high-risk conditions including: 7

• Dilatation of ascending aorta >45 mm 7
• Severe aortic stenosis 7
• Preterm labor while on oral anticoagulants 7
• Eisenmenger syndrome 7
• Severe heart failure 7
• Marfan syndrome with aortic diameter 40-45 mm (may be considered) 7

Management of Underlying High-Risk Conditions

Cardiovascular Disease

High-risk cardiac patients require management in specialized centers with multidisciplinary teams and on-site cardiac surgery capabilities. 7, 3

• Continue beta-blocker therapy throughout pregnancy for appropriate indications 3
• Perform regular echocardiograms for women with aortic aneurysm risk 3
• Vaginal delivery with epidural analgesia is preferred except for specific contraindications (dilated Marfan aortic roots, aortic dissection, uncorrected coarctation, pulmonary vascular disease) 7, 3
• Avoid epidural-induced vasodilatation in patients with cyanosis or compromised stroke output 7

Hypertensive Disorders

For severe hypertension, use oral nifedipine, IV labetalol, or IV hydralazine in a monitored setting. 3

• Avoid ACE inhibitors during second and third trimesters due to risk of fetal renal dysgenesis 7, 3
• Magnesium sulfate for seizure prophylaxis in preeclampsia 3
• Limit total fluid intake to 60-80 mL/hour to avoid pulmonary edema 3
• Delivery is the definitive treatment for preeclampsia 7, 3
• Low-dose aspirin for prevention in high-risk women 3
• Administer corticosteroids for 48 hours to accelerate fetal lung maturation if gestation <34 weeks 7

Diabetes Management

Strict glycemic control with insulin and medical nutrition therapy is essential, with referral to a registered dietitian to establish food plans and insulin-to-carbohydrate ratios. 7

• Preconception counseling should include comprehensive diabetes self-management education 7
• Screen for complications including retinopathy, nephropathy, and neuropathy 7
• Monitor for gestational diabetes, which carries a 2.35-fold increased risk in women with schizophrenia (as an example of psychiatric comorbidity increasing risk) 7

Delivery Planning and Mode

Vaginal delivery is recommended as first choice in most high-risk patients, with epidural analgesia and elective instrumental delivery considered for severe hypertension. 7

Coordinate birth for complex conditions through multidisciplinary teams in tertiary care centers with:

• Determination of optimal timing and mode of delivery well in advance 3
• Availability of all emergency support services 7
• Individualized anesthesia planning 7

For abnormal presentations specifically:

• Continuance of abnormal presentation at each subsequent week of the third trimester increases cesarean risk 2
• Only 15% of women with failed ECV deliver vaginally compared to 80% with successful ECV 6
• 10% of successful ECVs undergo spontaneous reversion to non-cephalic presentation 6

Postpartum Management

Continue close monitoring postpartum, especially for cardiovascular conditions, with assessment of physical and mental health risks. 3

• Anticipate potential postpartum hemorrhage in conditions like Ehlers-Danlos syndrome 3
• Provide immediate postpartum contraception for women at high risk in future pregnancies 3
• Schedule follow-up visits to ensure transition to appropriate ongoing care 3
• For women with prior VTE, postpartum prophylaxis with LMWH for 6 weeks is strongly recommended 8

Critical Pitfalls to Avoid

Do not perform single-timepoint risk assessment—risk is dynamic and requires continuous reassessment throughout pregnancy. 4

• Avoid saline abortion in cardiac patients due to risk of intravascular volume expansion, heart failure, and clotting abnormalities 7
• Do not use prostaglandin F compounds as they significantly increase pulmonary artery pressure and may decrease coronary perfusion 7
• Never overlook contextual factors including socioeconomic status, geographic location, and healthcare access that contribute to maternal outcomes 4
• Prophylactic antibiotic therapy during delivery is not recommended for endocarditis prevention 7