The most common cause of thrombocytopenia in the first trimester of pregnancy is ITP, which accounts for 11% of pregnancies and 51% of thrombocytopenia during pregnancy. According to the pathogenesis of ITP, patients have antibodies against their own platelets (PAIgG), which can not only destroy their own platelets and reduce them, but also enter the fetus through the placenta, damaging the fetal platelets and causing fetal thrombocytopenia. Therefore, the treatment of ITP combined with pregnancy must deal with two patients at the same time, namely the mother and the fetus.
1. Treatment of the mother in ITP combined with pregnancy
Once a woman with ITP becomes pregnant, her platelets will drop further and her symptoms will worsen. Therefore, in principle, it is better for women with ITP not to get pregnant, especially for patients with severe ITP (platelets <20×109/L), because in addition to further aggravation of the disease after pregnancy, treatment is also more difficult, because many treatments not only increase pregnancy complications, but also may have an impact on the fetus, so that many drugs cannot be applied as in non-pregnancy, and are often subject to many restrictions. The treatment varies according to the degree of thrombocytopenia in the mother and is described below.
111 Treatment of mild ITP (platelets >50×109/L, no clinical signs of bleeding)
Patients can usually have a normal pregnancy and do not need special treatment, they can take Amineptin 1g orally 3 times/d for a long time without side effects. However, we should pay attention to avoid cold and trauma, live a regular life and closely observe the bleeding tendency of the whole body, and do platelet count check regularly (once a month or so), and treat as below when it is aggravated.
112 Treatment of moderate ITP [platelets (20-50)×109/L]
Patients usually present with varying degrees of bleeding, and the preferred treatment is controversial. Although glucocorticoids are preferred in non-pregnant women, they have more side effects after pregnancy, such as gestational diabetes, osteoporosis, weight gain, and increased risk of preeclampsia due to elevated blood pressure. If there are no other contraindications in the second trimester, it can be used.
This drug is effective, easy to apply and inexpensive. The application method and dosage are the same as those for non-pregnant patients, except that the weight should not be calculated according to the weight at the time of pregnancy, but according to the weight before pregnancy, and the dosage should be reduced to the lowest effective maintenance dosage when it is effective. The best treatment for ITP combined pregnancy with minimal side effects is intravenous high-dose gammaglobulin, which should be used if the bleeding symptoms are significant, although the platelet count is not too low (possibly combined with abnormal platelet function).
The dosage is the same as in non-pregnancy, except that the weight is calculated according to the weight before pregnancy. Because the half-life of gammaglobulin is about 10 days, it can be maintained by replenishing 10g intravenously every 10 days or so if necessary to maintain the effective concentration. The biggest disadvantage of this drug is that it is too expensive, and should be preferred if available. Other drugs that can be used in non-pregnant patients, such as vincristine, cyclophosphamide, danazol, etc., have side effects that cause fetal malformations and are contraindicated. Other general management is the same as for patients with mild ITP.
113 Treatment of severe ITP (platelets <20×109/L)
If pregnancy occurs accidentally, abortion should be performed as soon as possible. Before abortion, dexamethasone 10-20 mg should be given intravenously for 3 days, and on the third day, 1 unit of platelets should be transfused to make platelets >50×109/L. After abortion, the patient should be treated according to the conventional treatment plan for ITP. If the patient insists to continue the pregnancy, it is more dangerous and difficult to handle, so she should be treated in the hematology ward. If the treatment is not successful after more than 1 month, splenectomy may be considered after weighing the advantages and disadvantages. The entire pregnancy should be observed and treated in the obstetrics and gynecology department and the hematology department.
114 Management at delivery
Patients with moderate or severe ITP who still have low platelets should be admitted to the obstetric ward about half a month before the expected date of delivery to continue to receive treatment to raise platelets and reduce bleeding, and the obstetrician should choose the appropriate mode of delivery according to the patient’s specific situation to help the mother and fetus to deliver. The emergency measures to raise platelets before delivery are triple therapy.
(1) glucocorticoids: dexamethasone is usually given intravenously 3 to 5 days before delivery
(2) intravenous platelet concentrate infusion: 1 unit of platelets (platelets ≥ 250×109/L) on the day of delivery, and 1 unit of platelets during or after delivery
(3) If the economic condition allows, it is better to give intravenous gammaglobulin, 20g/d, for 5 days one week before delivery. After delivery, treat according to ITP routine.
2.Birth thrombocytopenia and its management
Newborns delivered by pregnant women with ITP are likely to suffer from thrombocytopenia at the same time. According to the literature, about 10% of newborns have platelets ≤50×109/L, and about 5% have platelets ≤20×109/L. It is difficult to detect fetal platelets before delivery or to predict the number of platelets, but the degree of fetal thrombocytopenia may be related to the following factors.
(1) Maternal PAIgG concentration: High PAIgG concentration predisposes to severe fetal thrombocytopenia, while low PAIgG concentration predisposes to mild or no thrombocytopenia.
(2) Fetal megakaryocyte proliferation: those with good proliferation may have less thrombocytopenia.
(3) The ability of the fetal mononuclear macrophage system to clear platelets: Generally, the fetal mononuclear macrophage system is poor before delivery, so when the fetus is in the mother’s body, thrombocytopenia is generally small and not too heavy, but after delivery, because of its rapid increase in function, platelets can fall, reaching a minimum within 1 week, and then gradually rebound and return to normal.
(4) Pregnant women who have delivered thrombocytopenic infants often have thrombocytopenia in their second pregnancies: because fetal thrombocytopenia is generally self-limiting and can recover on its own within a short period of time, so generally no treatment is needed. If necessary, intravenous platelet concentrate can be given.