The First Trimester

Women with bleeding disorders are at increased risk for obstetric complications in the first trimester of pregnancy. Embryo implantation, miscarriage, molar and ectopic pregnancy are all associated with bleeding. Miscarriage (loss before 24 weeks’ gestation) complicates 10% to 15% of pregnancies. Bleeding associated with miscarriage may be heavy, depending on the gestational age at the time of loss. Some women choose to pass early pregnancies at home, whereas others prefer to have surgical evacuations by vacuum aspiration or dilation and curettage. Because they are at increased risk of uncontrolled hemorrhage, women with bleeding disorders are typically best served by a surgical evacuation, which requires careful surgical planning. Molar pregnancies are rare, occurring in approximately 0.1% of pregnancies. Bleeding is a hallmark of molar pregnancy, and surgical evacuation is required.

The Second Trimester

Women with hematologic disorders may desire invasive testing for aneuploidy in the second trimester. Options include chorionic villus sampling (CVS) and amniocentesis. In CVS, a biopsy of the placenta is taken between 11 and 14 weeks’ gestation. This procedure may entail more risk for women with bleeding disorders and special precautions such as pretreating with desmopressin acetate (DDAVP), or blood products should be considered. Amniocentesis is associated with a lower risk for bleeding; however, the risks and benefits of the procedure should still be addressed with the patient and her obstetrician. Prophylactic anticoagulation is often held for 1 day before either procedure, particularly CVS, depending on provider preference.

The Third Trimester

A small number of women experience complications that put their health, or the health of their fetus, at risk. These typically occur in the third trimester. Three of the most common, and those most likely to be affected by hematologic disease, are placental abruption, placenta previa, and preterm labor. A careful obstetric history may help to stratify the risks, because complications frequently recur. These complications are often unpreventable and of sudden onset, a carefully documented emergency management plan is essential.

Labor and Delivery: Specific Concerns

Many women who pass easily through their pregnancies are surprised at the level of planning and risk that delivery entails. Coordination between multiple teams is often required, including obstetrics (generally maternal fetal medicine specialists, if available), hematology, anesthesia, blood bank, and nursing, and it is never too early to start planning. As discussed earlier, many women have unexpected pregnancy complications, including bleeding and preterm labor, and a carefully laid plan can prevent substantial maternal and fetal morbidity.

A detailed labor and delivery plan should discuss mode of delivery, anesthesia concerns, and specific risks to the mother or fetus related to the hematologic disorder in question. In specific cases, it may also be helpful to provide the patient with a copy of her delivery plan, particularly if she lives at distance from the hospital or is planning to travel.

Pregnant women with medical disease are often advised to schedule delivery either by induction of labor or cesarean section, to optimize safety surrounding the delivery or to allow postpartum therapies that are contraindicated during pregnancy. Most of these deliveries can be undertaken in the 39th week, when fetal outcomes are optimized, but before many women have entered into spontaneous labor. There are some cases in which delivery before 39 weeks is indicated, most notably when maternal medical needs outweigh the small risks of late preterm birth to the fetus. The earlier in gestation that induction of labor is undertaken, the more likely that the uterine cervix is unfavorable, which increases the duration of the induction.

Both induction of labor and cesarean delivery carry significant risks. There are few strict indications for cesarean section. Inarguable maternal indications include a history of several different types of uterine surgery or abnormal placentation (placenta previa or accreta). Women may also have uncommon medical or physical conditions for which cesarean delivery is preferred, such as an inability to obtain lithotomy position, or pelvic contractures. Strict fetal indications include malpresentation (the presenting fetus is persistently breech or transverse) and some fetal anomalies, for example neural tube defect. Cesarean delivery is also commonly performed for several other reasons, including maternal request and suspected fetal macrosomia. Indications for cesarean delivery must be individualized, but most women are candidates for vaginal birth.

Induction of labor is achieved through use of vaginal prostaglandins, mechanical dilation, and intravenous (IV) oxytocin. During the period of cervical ripening, most women are not yet in labor, and may not be for another 24 hours or longer. For those with a prior vaginal birth, delivery may be attained in under one day. Without a prior vaginal birth, induction is less predictable and may take several days, depending on provider and patient tolerance. Some women experience minor bleeding during cervical dilation; however, most bleeding occurs around delivery. Bleeding continues until vaginal lacerations are repaired and uterine tone is achieved, typically within 40 minutes after the infant’s birth. Typical blood loss for vaginal birth is less than 500 mL.

Cesarean section accounts for more than 30% of deliveries. The operation is typically performed through a transverse lower abdominal skin incision, and transverse uterine incision. The duration of surgery is commonly 30 to 60 minutes, with blood loss under 1000 mL. The procedure can be scheduled at the convenience of the obstetric and medical teams, often making it an appealing option. Nonetheless, cesarean delivery carries greater maternal risks of hemorrhage and infection than does vaginal delivery, and increases the chance of abnormal placentation in a future pregnancy. With each surgery, these risks rise. Incidence of thromboembolic disease is also increased for 6 weeks postpartum. For all of these reasons, cesarean delivery should only be performed with appropriate indications.

For both vaginal birth and cesarean delivery, careful consideration must be given to the management timeline. At any point during a labor induction, an emergent delivery might become necessary. Anticoagulation is held during labor for all but the most critical indications (eg, artificial heart valves, severe prothrombotic states). For that reason, some would recommend a cesarean delivery to limit the time off anticoagulation; however, surgery increases the risk of postpartum clot formation compared with vaginal delivery. In addition, vaginal delivery is less likely to be complicated by postdelivery bleeding that would be worsened by anticoagulation. In a carefully monitored setting, with appropriate anesthesia and blood bank support, women may be anticoagulated during labor, with anticoagulation held at delivery and in the immediate postpartum period. This strategy should be reserved for the most critically ill patients who have a life-threatening risk of thrombosis.

A woman who requires platelet or other transfusion support would have a different scenario. For that patient, consideration must to given to frequency of laboratory evaluation, and timing and indications for transfusion. If the patient is to be induced, should transfusions begin on admission, in the active phase of labor, or when delivery is imminent? For the patient requiring platelets, should transfusions be initiated if platelets decline, or when they reach a certain threshold? Every patient should also have an emergency backup plan, in case of complications such as a transfusion reaction or the need for an unscheduled cesarean delivery.

The importance of communication among various members of the team cannot be overstated. Before delivery, it is helpful to have a detailed discussion regarding what complications from the pregnancy and disease may be anticipated, as well as any known complications of therapy. In addition, definition of critical laboratory values and an algorithm with which to treat them are essential. If an induction is planned, clear communication with the blood bank to ensure adequate stocking of the appropriate products and preparation of medications is also of key importance. If adequate products cannot be assured, consideration should be given to transfer of the patient to a facility with appropriate resources.

Fetal Concerns

An important consideration when caring for pregnant women with medical disease is the risk that the fetus will either inherit the disease in question, or be affected by the mother’s condition. Any woman with a potentially heritable disorder should be offered genetic counseling before pregnancy or early in gestation, because genetic testing for the fetus may be possible. Understanding fetal risk is also essential for delivery planning. If the fetus has a known or suspected bleeding disorder, or, as in ITP, there is concern for neonatal thrombocytopenia, operative vaginal delivery (forceps or vacuum-assisted delivery) is contraindicated, as is fetal monitoring using a scalp electrode. In these infants, profound thrombocytopenia may develop in the first days of life, therefore communication with the pediatric team is essential.