Management of ITP in Pregnancy
Corticosteroids (prednisone 10-20 mg/day) are the recommended first-line treatment for pregnant women with ITP requiring therapy, with IVIg reserved for corticosteroid failure, significant side effects, or when rapid platelet increase is needed. 1
Treatment Thresholds
Treatment is indicated when:
- Platelet count falls below 20,000-30,000/μL, even if asymptomatic 1
- Any symptomatic bleeding occurs, regardless of platelet count 1
No treatment is required when:
- Platelets remain ≥30,000/μL during the first two trimesters without bleeding 1
- Most pregnant women with ITP history (58%) do not require treatment during pregnancy 2
First-Line Treatment: Corticosteroids
Prednisone 10-20 mg/day should be initiated and adjusted to the minimum dose that maintains a hemostatic platelet count. 1 Corticosteroids and IVIg demonstrate comparable effectiveness, with mean maternal platelet counts at delivery of 77 × 10⁹/L versus 69 × 10⁹/L respectively, and similar response rates of 39% versus 38% 2. The choice between these agents depends on clinical urgency and side effect profile rather than efficacy differences.
Second-Line Treatment: IVIg
IVIg should be used when corticosteroids are ineffective, cause significant side effects, or when more rapid platelet increase is required. 1 Single IVIg infusions are well tolerated and may be repeated as needed to prevent hemorrhage and achieve adequate platelet counts for delivery 3. IVIg produces a mean platelet increase of 46 × 10⁹/L approximately 3 days after administration 4.
Alternative Second-Line Options
For non-splenectomized Rh(D)-positive patients:
- IV anti-D 50-75 μg/kg is effective and safe in the second and third trimesters 3
- Augmentation with corticosteroids or IVIg is usually required to achieve target platelet count of 50 × 10⁹/L 3
- Monitor for neonatal jaundice, anemia, and direct antiglobulin test positivity after delivery 3
Refractory Cases
For patients failing first-line therapy, consider:
- Combining first-line treatments in the weeks before delivery 3
- High-dose methylprednisolone (1000 mg) possibly combined with IVIg or azathioprine 3
- Azathioprine is safe during pregnancy based on SLE and renal transplantation data, though response is slow 3
- Cyclosporin A has not been associated with significant maternal or fetal toxicity 3
Splenectomy considerations:
- Best performed in the second trimester if necessary 3
- May be performed laparoscopically, though technically difficult beyond 20 weeks' gestation 3
- Appropriate vaccination during or after pregnancy is required 3
Delivery Management
The mode of delivery should be determined by obstetric indications alone, not by maternal platelet count. 1 There is no evidence that cesarean section is safer for the thrombocytopenic fetus than uncomplicated vaginal delivery 3. The neonatal mortality rate for babies born to mothers with ITP is less than 1%, with intracranial hemorrhage occurring in only 0-1.5% of thrombocytopenic infants 3.
Target platelet count at delivery:
- Aim for 100 × 10⁹/L at delivery 4
- 45% of pregnancies reach this target, while only 7% have platelets <50 × 10⁹/L at delivery 4
Prophylactic platelet transfusions are appropriate when:
- Platelets <10,000/μL with planned cesarean section 1
- Epistaxis or mucous membrane bleeding with expected vaginal delivery 1
Neonatal Management
Critical monitoring requirements:
- Check neonatal platelet count for 3-4 days after birth 1
- 28% of neonates have platelet counts <150 × 10⁹/L at birth, and 9% have counts <50 × 10⁹/L 2
- Nadir platelet counts typically occur at birth but may occur up to 6 days postnatally 2
Risk factors for neonatal thrombocytopenia:
- Maternal platelets <20 × 10⁹/L during pregnancy confer five-fold increased risk 4
- Prior neonatal thrombocytopenia confers eight-fold increased risk 4
Treatment indications:
- Consider brain imaging if platelet count at birth is <20,000/μL 1
- IVIg is appropriate if infant's platelets <20,000/μL without evidence of intracranial hemorrhage 1
Critical Pitfalls to Avoid
Do not perform fetal blood sampling by cordocentesis - it carries a 1-2% fetal mortality risk, at least as high as the risk of intracranial hemorrhage 3. Fetal or neonatal platelet count cannot be reliably predicted by maternal platelet count, platelet antibody levels, or history of maternal splenectomy 3.
Antiplatelet antibody testing has no value in routine diagnosis. 1
Most hemorrhagic events in neonates occur 24-48 hours after delivery at the nadir of the platelet count, not during delivery itself 3.