Disease Description (Causes and Symptoms)
- Definition: A condition in which two or more fetuses are simultaneously present in a pregnancy (twins, triplets, etc.).
- Causes and pathophysiology
- The cause is unknown in most cases. The frequency of dizygotic (fraternal) twins increases with a family history, advanced maternal age, ovulation induction, and the use of assisted reproductive technologies (in vitro fertilization and ovulation-inducing drugs).
- Monozygotic (identical) twins occur through the division of a fertilized egg, and the risk of complications varies depending on the type of placenta (chorionicity) and amniotic sac (amnionicity). In monochorionic pregnancies (a shared placenta), the risk of blood-flow imbalance complications such as twin-to-twin transfusion syndrome (TTTS) increases due to vascular anastomoses between the fetuses.
- Uterine overdistension and competition between fetuses increase the risk of preterm birth, low birth weight, and other complications.
- Main symptoms
- Early symptoms are similar to those of a singleton pregnancy, but morning sickness (nausea and vomiting) is often more severe.
- The abdomen is larger than expected for the gestational age; ultrasound confirms two or more fetuses and multiple heartbeats.
- If complications occur during pregnancy (preterm labor, preeclampsia, placental abnormalities, etc.), symptoms such as headache, visual disturbances, abdominal pain, vaginal bleeding, and decreased fetal movement may occur.
Treatment Methods and Precautions
- Prenatal care (standard treatment)
- Ultrasound and monitoring of fetal movement and growth: After confirming the placental and amniotic sac status (chorionicity/amnionicity) by ultrasound, frequent monitoring is performed according to the risk level. (In particular, ultrasound every 2 weeks after 16 weeks is recommended for monozygotic twins.)
- Periodic growth assessment (at shorter intervals), with NST/Doppler examinations performed when necessary.
- Anemia and nutritional management: More calories, protein, iron, folate, and other nutrients are needed than in a singleton pregnancy. Nutritional counseling may be provided depending on the clinical situation.
- Complication management: Immediate medical attention is required for preeclampsia, gestational diabetes management (medication, hospitalization, and follow-up), placental abruption, placenta previa, and other conditions.
- Procedural and surgical treatment
- If specific complications such as severe TTTS occur: placental vascular laser treatment (laparoscopic or hysteroscopic fetoscopic laser ablation), or selective fetal reduction (considered in high-risk high-order multifetal pregnancies).
- Preterm delivery and cesarean section: Determined according to fetal presentation, number of fetuses, fetal condition, and gestational age.
- Delivery planning
- The timing and method of delivery are determined by comprehensively considering the placental and amniotic sac configuration, fetal presentation, and maternal and fetal conditions. Twins have a higher likelihood of preterm delivery and cesarean section.
- Lifestyle management and precautions
- Actively participate in regular prenatal examinations; check weight, edema, and blood pressure; visit the hospital immediately if decreased fetal movement, abdominal pain, or bleeding occurs.
- Do not smoke or drink alcohol; get adequate rest and eat a balanced diet; limit strenuous exercise (follow the doctor’s instructions).
- Complications (precautions)
- Preterm birth, low birth weight, preeclampsia (approximately twice the risk compared with a singleton pregnancy), placental abnormalities, intertwin blood-flow imbalance (TTTS), increased congenital anomalies (relatively increased in monozygotic twins), postpartum hemorrhage, and others.
- Prognosis
- Maternal and neonatal risk varies greatly depending on the number of fetuses, chorionicity, and the level of prenatal care. Prognosis can be improved through active monitoring and appropriate intervention.
Checklist Before an Outpatient Visit (Items to Bring and Example Questions)
- Items to bring
- List of currently used medications and supplements (names and dosages)
- Results of previous prenatal examinations and ultrasounds (printed copies/files if possible)
- Existing medical history (hypertension, diabetes, surgeries, etc.) and family history (including a history of twins)
- Symptom records: severity of morning sickness, weight changes, changes in fetal movement, and whether bleeding, abdominal pain, headache, or visual disturbances have occurred
- Results of pregnancy-related tests (blood tests, urine tests, etc.)
- Examples of questions to prepare in advance for the outpatient visit
- What are the recent trends in my weight, edema, and blood pressure?
- What is the number of fetuses and the placental status (chorionicity), and what do they mean?
- What complications have been diagnosed, if any, and what is the future management plan?
Examples of General Questions to Ask the Doctor
- "What are the placental and amniotic sac configurations (chorionicity/amnionicity) in my pregnancy, and what risks do they imply?"
- "How often are ultrasounds and tests recommended, and when is the expected timing of delivery (gestational age)?"
- "What is the likelihood that hospitalization will be necessary, and what are the criteria for deciding the delivery method (vaginal delivery vs. cesarean section)?"
- "What symptoms should I watch for in this pregnancy (symptoms that require me to come to the hospital immediately)?"
Examples of condition-specific questions
- "Has it been confirmed whether the twins are monozygotic (monochorionic)? If they are monochorionic, how will the risk of TTTS be monitored and managed?"
- "If there is currently a difference in the fetuses’ growth, at what point is it considered risky (what is the management plan if growth restriction occurs)?"