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 |
Abnormalities of Placenta and Cord
Placental Abnormalities
1. Placenta Previa
- Placenta implanted over or near the internal cervical os.
- Painless, bright red vaginal bleeding in the third trimester.
- Diagnosed by transvaginal ultrasound.
- C-section is the preferred delivery mode.
2. Placental Abruption
- Premature separation of a normally implanted placenta before delivery.
- Painful vaginal bleeding, Rigid uterus, Fetal distress.
- Risk factors: Hypertension, Trauma, Smoking.
- Emergency C-section if fetal distress.
3. Placenta Accreta Spectrum
- Placenta abnormally adheres to the uterine wall.
- Types:
- Accreta (Superficial attachment).
- Increta (Invades myometrium).
- Percreta (Penetrates through uterus).
- Risk Factors: Previous C-sections, Placenta previa.
- Management: Planned C-section ± Hysterectomy.
Umbilical Cord Abnormalities
1. Cord Prolapse
- Umbilical cord descends before the fetal presenting part.
- Causes: Premature rupture of membranes (PROM), Breech presentation.
- Management: Emergency C-section to prevent fetal hypoxia.
2. Nuchal Cord
- Cord wrapped around fetal neck.
- If tight, can cause fetal distress during labor.
- Detected on ultrasound & managed during delivery.
3. Velamentous Cord Insertion
- Cord inserts into membranes instead of the placenta.
- Risk of vasa previa (Fetal blood vessels crossing cervix).
- If diagnosed antenatally, C-section is recommended.
Summary Table: Multiple Pregnancy & Placental Abnormalities
|
Condition |
Key Features |
Management |
|
Multiple Pregnancy |
DCDA, MCDA, MCMA classification |
Growth monitoring, Mode of delivery based on type |
|
TTTS |
Unequal twin growth, Poly-oligo sequence |
Amnioreduction, Laser therapy |
|
Placenta Previa |
Painless bleeding, No fetal distress |
C-section |
|
Placental Abruption |
Painful bleeding, Rigid uterus, Fetal distress |
Emergency C-section |
|
Placenta Accreta |
Abnormally attached placenta |
C-section ± Hysterectomy |
|
Cord Prolapse |
Cord below presenting part, Fetal bradycardia |
Emergency C-section |
Key Takeaways
- Twin pregnancy is classified based on chorionicity & amnionicity.
- Monochorionic twins are at risk of TTTS.
- Placenta previa causes painless bleeding; Abruption causes painful bleeding.
- Cord prolapse is an emergency requiring immediate C-section.
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