The Society for Maternal-Fetal Medicine (SMFM) recently released updated clinical checklists to guide the management of monochorionic twin pregnancies, a high-risk group that requires intensive surveillance and coordinated care throughout gestation. The revised tools reflect evolving evidence and updated practice recommendations aimed at reducing complications, preventing errors of omission, and improving perinatal outcomes.¹

Rising twin pregnancies and unique risks of monochorionicity

Although twin birth rates in the United States have declined modestly over the past decade, twin gestations remain significantly more complex than singleton pregnancies. All twin pregnancies carry higher risks of maternal and perinatal complications, including hypertensive disorders, preterm birth, fetal growth restriction, stillbirth, and neonatal death, according to SMFM.

Approximately 20% of twin pregnancies are monochorionic, meaning the fetuses share a single placenta. This placental architecture introduces additional risks because of vascular connections between the twins, which can lead to complications such as twin-twin transfusion syndrome, twin anemia-polycythemia sequence, and twin reversed arterial perfusion sequence. These conditions affect an estimated 15% of monochorionic twin pregnancies. Monoamniotic twins, a rare subset, face particularly high stillbirth risk related to umbilical cord entanglement.

The role of structured management

Many complications associated with monochorionic twin pregnancy can be prevented, treated, or mitigated with timely intervention. Strategies include low-dose aspirin to reduce preeclampsia risk, early delivery to lower stillbirth risk, laser therapy for placental vascular complications, and enhanced ultrasound surveillance to detect abnormalities or growth discordance.

However, the complexity and timing of these interventions create opportunities for missed or delayed care. SMFM emphasizes that cognitive aids such as checklists can help standardize care and reduce preventable gaps, especially in busy clinical settings.

What’s new in the updated checklists

SMFM originally published checklists for monochorionic/diamniotic and monochorionic/monoamniotic twin pregnancies in 2020. The updated versions incorporate several important changes aligned with current guidance.

Key updates include the addition of first-trimester detailed fetal anatomy ultrasonography to improve early detection of congenital anomalies, removal of selective termination language from counseling sections, and updated recommendations for Doppler surveillance to screen for twin anemia-polycythemia sequence. Growth assessment intervals for uncomplicated pregnancies are now specified as every 4 weeks.

Below is a re-creation of the updated checklists:

Pregnancy management checklist: Monochorionic diamniotic (MC/DA) twin gestation

• This checklist is a sample and should be modified as needed to fit local practice circumstances.
• All elements of routine prenatal care are assumed.
• Checklist shows additional items for MC/DA twins.

Patient Information

• (Patient Sticker Here) or Enter:
  • Name ________________________________
  • DOB _________________________________
  • Record # _____________________________
  • EDD (40 weeks): ______________________
  • Planned delivery (weeks): _____________
  • Planned delivery date: ________________

Counseling About Risks of MC/DA Twins

Document discussion of:

• ☐ Fetal anomalies
• ☐ Complications of monochorionicity, including twin-twin transfusion syndrome, twin anemia-polycythemia sequence
• ☐ Pregnancy complications, including spontaneous preterm birth, growth restriction, preeclampsia/hypertension, gestational diabetes, and postpartum hemorrhage
• ☐ Intrauterine fetal death including potential sequelae to a surviving co-twin

First Trimester

• ☐ Ultrasound to establish EDD, chorionicity, and amnionicity, before 14 weeks of gestation.
• ☐ Ultrasound for detailed fetal anatomy evaluation at 12 0/7–13 0/7 weeks of gestation.
• ☐ Low-dose aspirin starting at 12 to 28 weeks of gestation, optimally before 16 weeks of gestation

Monitoring and Surveillance

• ☐ Serial ultrasound exam starting at 16 weeks of gestation
  • ☐ Every 2 weeks for assessment of amniotic fluid deepest vertical pocket and bladder filling
  • ☐ Consider umbilical artery and middle cerebral artery Doppler evaluation with routine surveillance depending on local resources and patient access to care
  • ☐ Every 4 weeks for evaluation of fetal growth
• ☐ Detailed fetal anatomy survey at 18 to 22 weeks of gestation (or earlier if technically feasible).
• ☐ Fetal echocardiogram at 18 to 22 weeks of gestation
• ☐ Antenatal fetal surveillance (nonstress test or biophysical profile), weekly starting at 32 0/7 weeks for uncomplicated MC/DA twins, individualized in consultation with maternal-fetal medicine specialist for complicated MC/DA twins.
• ☐ Prophylactic cerclage and prophylactic progesterone are not recommended.

Delivery

• ☐ Antenatal corticosteroids within 7 days before delivery if delivery anticipated before 34 weeks of gestation
• ☐ Planned delivery between 34 0/7 and 37 6/7 weeks of gestation, possibly earlier if complications.
• ☐ Consider vaginal birth in vertex presentation of presenting twin, gestational age at least 32 weeks, available obstetrician experienced with management of non-vertex second twin presentation, and shared decision making with patient.

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Pregnancy management checklist: Monochorionic monoamniotic (MC/MA) twin gestation

• This checklist is an example and should be modified as needed to fit local practice circumstances.
• All elements of routine prenatal care are assumed.
• Checklist shows additional items for MC/MA twins.

Patient Information

• (Patient Sticker Here) or Enter:
  • Name ________________________________
  • DOB _________________________________
  • Record # _____________________________
  • EDD (40 weeks): ______________________
  • Planned delivery (weeks): _____________
  • Planned delivery date: ________________

Counseling About Risks of MC/MA Twins

Document discussion of:

• ☐ Fetal anomalies
• ☐ Complications of monochorionicity, including twin-twin transfusion syndrome, twin anemia-polycythemia sequence
• ☐ Complications of cord entanglement
• ☐ Pregnancy complications, including spontaneous preterm birth, growth restriction, preeclampsia/hypertension, gestational diabetes, and postpartum hemorrhage
• ☐ Intrauterine fetal death including potential sequelae to a surviving co-twin
• ☐ Planned antepartum surveillance regimen (inpatient vs outpatient)
• ☐ Planned cesarean delivery; complications with early preterm delivery

First Trimester

• ☐ Ultrasound to establish EDD, chorionicity, and amnionicity, before 14 weeks of gestation.
• ☐ Ultrasound for detailed fetal anatomy evaluation at 12 0/7–13 0/7 weeks of gestation.
• ☐ Low-dose aspirin starting at 12 to 28 weeks of gestation, optimally before 16 weeks of gestation

Monitoring and Surveillance

• ☐ Serial ultrasound exam starting at 16 weeks of gestation
  • ☐ Every 2 weeks for assessment of amniotic fluid volume and bladder filling
  • ☐ Consider umbilical artery and middle cerebral artery Doppler evaluation with routine surveillance depending on local resources and patient access to care
  • ☐ Every 4 weeks for evaluation of fetal growth
• ☐ Detailed fetal anatomy survey at 18 to 22 weeks of gestation (or earlier if technically feasible).
• ☐ Fetal echocardiogram at 18 to 22 weeks of gestation
• ☐ Antepartum surveillance (nonstress test or biophysical profile), starting gestational age and frequency individualized in consultation with maternal-fetal medicine specialist.

Delivery Planning

• ☐ Antenatal corticosteroids within 7 days before anticipated delivery
• ☐ Planned cesarean delivery at 32 0/7 to 34 0/7 weeks of gestation, or earlier if complications

The checklists also clarify timing for antepartum fetal surveillance, recommend updated delivery windows for monochorionic/diamniotic twins, and support vaginal birth in select cases when conditions and expertise allow. Design elements follow best practices for clinical checklists, emphasizing clarity, simplicity, and ease of use.

Implementing checklists in clinical practice

SMFM encourages practices to determine how best to integrate the checklists into their workflows, whether as digital tools embedded in electronic health records, paper forms included in patient charts, or reference documents used by care teams. Practices are advised to reach consensus on discretionary elements, such as Doppler use, hospitalization strategies for monoamniotic twins, and institution-specific delivery timing.

The statement also underscores the importance of revisiting and updating checklists as evidence evolves, with clear version control to avoid confusion.

Measuring quality and addressing disparities

To assess the effectiveness of checklist implementation, SMFM proposes several quality indicators, including timely ultrasound examinations, aspirin initiation, fetal echocardiography, appropriate timing of delivery, and perinatal survival outcomes. Importantly, the organization recommends stratifying these metrics by race and ethnicity to identify and address disparities in care and outcomes.

Through these updated checklists, SMFM aims to support clinicians in delivering consistent, evidence-based care for monochorionic twin pregnancies and to improve outcomes for both pregnant individuals and their infants.

RELATED: SMFM outlines strategies to expand maternal-fetal medicine access in rural and underserved communities²

References:

1. Yao R, Hoskins IA, Combs CA, SMFM, SMFM Patient Safety and Quality Committee. Society for Maternal-Fetal Medicine Special Statement: Updated checklists for management of monochorionic twin pregnancy. Pregnancy. Published February 4, 2026. Accessed February 10, 2026. doi:10.1002/pmf2.70213
2. SMFM outlines strategies to expand maternal-fetal medicine access in rural and underserved communities. Contemporary OB/GYN. Published February 9, 2026. Accessed February 10, 2026. https://www.contemporaryobgyn.net/view/smfm-outlines-strategies-to-expand-maternal-fetal-medicine-access-in-rural-and-underserved-communities