Multiple pregnancy is a condition where two or more fetuses develop simultaneously in the uterus. The most common type is twin pregnancy.
Incidence:
- Twin pregnancy: 1 in 80 pregnancies.
- Triplets: 1 in 6400 pregnancies.
- Higher-order multiples: Less common but increasing due to ART (Assisted Reproductive Techniques).
Types of Twin Pregnancy
1. Zygosity-Based Classification:
- Dizygotic (Fraternal) Twins (70%)
- Two separate ova fertilized by two sperm.
- Always have two placentas (Dichorionic, Diamniotic).
- Common in advanced maternal age, ART, African ethnicity.
- Monozygotic (Identical) Twins (30%)
- Single ovum fertilized by one sperm, then splits.
- Chorionicity depends on the time of division:
|
Day of Division |
Chorionicity |
|
0–3 Days |
Dichorionic, Diamniotic
(DCDA) (Two placentas, Two sacs) |
|
4–7 Days |
Monochorionic, Diamniotic
(MCDA) (One placenta, Two sacs) |
|
8–12 Days |
Monochorionic, Monoamniotic
(MCMA) (One placenta, One sac) |
|
>13 Days |
Conjoined Twins (Incomplete separation) |
Diagnosis of Multiple Pregnancy
1. Clinical Features:
- Excessive maternal weight gain.
- Large-for-dates uterus.
- Two fetal heart sounds detected on Doppler.
2. Ultrasound (Gold Standard):
- First trimester:
- Number of gestational sacs and yolk sacs determine chorionicity.
- Second trimester:
- Lambda (λ) sign → Dichorionic.
- T-sign → Monochorionic.
3. Biochemical Markers:
- Higher β-hCG and Alpha-Fetoprotein (AFP) levels than normal pregnancy.
Complications of Multiple Pregnancy
Maternal Complications:
- Hyperemesis gravidarum (Severe vomiting).
- Gestational hypertension & preeclampsia.
- Gestational diabetes mellitus (GDM).
- Polyhydramnios.
- Preterm labor & preterm premature rupture of membranes (PPROM).
- Increased risk of cesarean section.
Fetal Complications:
- Preterm birth (Common in twins, >50% in triplets).
- Low birth weight & Intrauterine growth restriction (IUGR).
- Congenital anomalies.
- Twin-to-Twin Transfusion Syndrome (TTTS) in monochorionic twins.
- Cord entanglement in monochorionic-monoamniotic twins.
Twin-to-Twin Transfusion Syndrome (TTTS)
Definition:
- A condition occurring only in monochorionic twins due to vascular anastomoses in the placenta.
- One twin (Donor) becomes growth-restricted, and the other twin (Recipient) becomes polycythemic.
Clinical Features:
- Donor Twin: Small, Oligohydramnios, Anemia.
- Recipient Twin: Large, Polyhydramnios, Heart failure.
Management:
- Amnioreduction (Remove excess amniotic fluid).
- Laser therapy to ablate vascular connections.
- Early delivery if severe.
Management of Multiple Pregnancy
Antenatal Care:
- Frequent ultrasounds for fetal growth monitoring.
- Serial Doppler studies for monochorionic twins.
- Iron & folic acid supplementation to prevent anemia.
- Monitor for signs of preterm labor.
Delivery Plan:
|
Type of Twins |
Mode of Delivery |
|
Dichorionic-Diamniotic
(DCDA) |
Vaginal if both heads down |
|
Monochorionic-Diamniotic
(MCDA) |
C-section preferred due to TTTS risk |
|
Monochorionic-Monoamniotic
(MCMA) |
Mandatory C-section at
32–34 weeks |
|
Triplets or Higher |
C-section mandatory |
Summary Table: Multiple Pregnancy
|
Feature |
Dizygotic (Fraternal) Twins |
Monozygotic (Identical) Twins |
|
Cause |
Two ova fertilized |
Single ovum splits |
|
Chorionicity |
Always Dichorionic-Diamniotic |
Varies (DCDA, MCDA, MCMA,
Conjoined) |
|
Complications |
Less severe |
Higher risk of TTTS, IUGR,
Cord accidents |
|
Delivery |
Vaginal or C-section |
Mostly C-section |
Key Takeaways
- Dichorionic twins have lower risk compared to monochorionic twins.
- TTTS occurs only in monochorionic twins.
- Monoamniotic twins have a high risk of cord entanglement.
- C-section is mandatory for MCMA and triplet pregnancies.
