Art & Science of Midwifery 4 * Lecture Multiple Pregnancy 2025 11 March 2025

Introduction to Multiple Pregnancy

• The session covers various aspects related to multiple pregnancies, specifically twins.

• The discussion involves definitions, management, midwifery roles, and complications associated with twin pregnancies.

Types of Twins

Monozygotic Twins

• Definition: Formed from one ovum fertilized by one sperm that divides into two identical twins.

• Incidence: Accounts for approximately 25-30% of twin pregnancies; least common.

• Characteristics: Identical genetic material, no family history influence on occurrence.

Dizygotic Twins

• Definition: Formed from two separate eggs, each fertilized by its own sperm.

• Incidence: Accounts for around 70-75% of twin pregnancies; more common than monozygotic twins.

• Characteristics: Non-identical, each twin has separate gestational sacs with their own placentas.

Twin Classification by Chorionicity and Amnionicity

• Understanding whether twins are monozygotic or dizygotic is crucial for management strategies.

Chorionicity

• Dichorionic: Two placentas (i.e., typical dizygotic twins), each with its own corion.

• Monochorionic: One placenta shared between both twins, possible with monozygotic twins.

Amnionicity

• Diamnionic: Two separate amniotic sacs (more common).

• Monoamnionic: One amniotic sac (less common, higher risk).

Importance of Early Ultrasound

• Ultrasound scans performed before 14 weeks help determine chorionicity and amnionicity which influence management.

• The fusion of chorions after this period makes it difficult to assess the individual sacs, impacting caregiver decisions.

Complications of Monozygotic Twins

• Twin-to-Twin Transfusion Syndrome: Risk due to shared placental blood supply, leading to growth discrepancies between twins.

• Symptoms: Disproportionate growth detected through ultrasound scans.

• Requires careful monitoring and potential surgical intervention (e.g., laser ablation of shared vessels).

Care Management in Twin Pregnancies

• Comprehensive monitoring is essential, given the higher risks (e.g., anemia in the birthing person, growth issues in twins).

• Regular collaboration between obstetricians and midwives is crucial for effective management and referral.

Case Study of Anna's Twin Pregnancy

• Overview of Anna's experience: Previous cesarean section, significant nausea, and fatigue.

• Twin pregnancy was confirmed early via ultrasound; managed with shared care between midwife and obstetric team.

• Regular scans and communication facilitated monitoring of both pregnancies.

Delivery and Postnatal Care

• Emphasis on careful monitoring during labor: Continuous CTG recommended to distinguish fetal heart rates.

• Management considerations involve preparing for potential cesarean deliveries if complications arise during labor.

• Postnatal care includes support for both mother and twins, ensuring proper health evaluations.

Conclusion

• Multiple pregnancies present unique challenges and require a collaborative approach between healthcare providers.

• Knowledge of twin types, their risks, and appropriate care management strategies is imperative in delivering safe outcomes for both mother and infants.

Twin Classification by Chorionicity

• Dichorionic Twins:

  • DCDA: Two chorions (two placentas), two amnions (two separate sacs). Occurs in approximately 30% of cases; still identical twins.

  • MCDA: One chorion, two amnions (one placenta). Occurs in about 70% of cases.

• Monochorionic Twins:

  • MCMA: One chorion, one amnion (one placenta). Very rare, occurring in less than 1% of cases.

Importance of Chorionicity

• Chorionicity is determined by the stage of embryogenesis at which the single fertilized ovum splits.

• Later splits may lead to complications and the need for careful monitoring.

Care Management of Multiple Pregnancies

• LMC (Lead Maternity Carer) midwifery care is vital for the antenatal care of multiple pregnancies.

• Effective management ensures better outcomes for both the mother and the twins during birth and beyond.