The bone marrow, a soft, spongy tissue found within bones, serves as the body’s primary factory for producing blood cells. This system generates red blood cells (carrying oxygen), white blood cells (fighting infection), and platelets (aiding clotting). Healthy bone marrow is fundamental for overall well-being. This article explores how bone marrow health, especially concerning transplants or certain conditions, influences pregnancy and its success rates.
Bone Marrow Transplant and Fertility
Bone marrow transplantation (BMT), also known as hematopoietic stem cell transplantation (HSCT), often impacts fertility. Conditioning regimens before a transplant, involving high-dose chemotherapy or radiation, can damage reproductive organs. In women, this may lead to premature ovarian failure, where ovaries cease functioning prematurely. For men, these treatments can reduce sperm production and quality.
Fertility impairment depends on drugs, dosages, and patient age at transplant. Younger patients, especially those under 26 receiving transplants for severe aplastic anemia, are more likely to retain normal gonadal function than older patients or those treated for hematological malignancies. Allogeneic transplants, where donor immune cells may attack reproductive organs (graft-versus-host disease, or GVHD), can cause further damage.
Given these risks, discussing fertility preservation options with a healthcare team before BMT is recommended. For women, choices include freezing eggs or embryos, with embryo freezing potentially offering better survival after thawing. Ovarian tissue freezing is another, experimental option. Men can typically bank sperm before treatment.
While fertility can be impaired, conception remains possible for some individuals after BMT, sometimes even spontaneously. This highlights the importance of counseling on contraception for those not planning pregnancy. Research aims to improve fertility preservation and understand long-term reproductive outcomes for transplant survivors.
Pregnancy Outcomes After Bone Marrow Transplant
For individuals who achieve pregnancy after a bone marrow transplant, outcomes can be encouraging, though increased monitoring is often needed due to potential risks. A German study of 74 pregnancies in women who underwent allogeneic hematopoietic cell transplantation (alloHCT) reported 57 (77%) resulted in live births. The CIBMTR reported live birth rates of 85% for female transplant patients and 86% for partners of male transplant patients. Most pregnancies occurred 5-10 years after the transplant.
Despite these positive live birth rates, several maternal risks are associated with pregnancy post-transplant. Complications can include organ toxicity or chronic graft-versus-host disease (GVHD) from previous conditioning regimens. Studies note a higher incidence of vascular problems and hypertension in pregnant alloHCT recipients. The uterus may also be more susceptible to radiation damage, increasing the risk of adverse pregnancy outcomes.
Fetal risks, while generally not involving more congenital anomalies than the general population, include prematurity and low birth weight. For example, a study found 20% of pregnancies after allogeneic stem cell transplant resulted in preterm delivery (compared to 6% generally), and 23% resulted in low birth weight infants (compared to 6% generally). Close pre-conception counseling is important to discuss individual risks based on disease, conditioning regimen, and time since transplant. Multidisciplinary care involving hematologists and obstetricians is recommended throughout pregnancy to manage potential complications.
Managing Pregnancy with Bone Marrow Conditions
Pregnancy for individuals with pre-existing bone marrow conditions, distinct from those who have undergone a transplant, presents unique considerations. Conditions such as aplastic anemia, myelodysplastic syndromes (MDS), or certain types of leukemia in remission require careful management for favorable maternal and fetal outcomes. Aplastic anemia, where bone marrow fails to produce enough blood cells, can lead to complications like hemorrhage and sepsis during pregnancy. While rare, successful pregnancies are possible with close monitoring and supportive care, like blood transfusions. Remission status of aplastic anemia may worsen after pregnancy, and preeclampsia risk has been observed.
For myelodysplastic syndromes, disorders where blood cells are poorly formed, pregnancy is considered high-risk due to complications like infections, bleeding, and anemia. Anemia and gestational hypertension are primary risk factors for poor maternal and fetal outcomes. Close monitoring of blood counts and active supportive treatment are recommended, with some studies suggesting hemoglobin levels above 70 g/L and platelet counts above 30 x 10^9/L. In selected cases of low-risk MDS, full-term pregnancies may be achievable.
When leukemia is in remission, pregnancy outcomes can still be affected. Women with a history of leukemia or leukemia in remission show increased risks of gestational diabetes, threatened preterm labor, and venous thromboembolism. Newborns may also have a higher incidence of preterm deliveries and congenital anomalies. Managing these pregnancies requires close collaboration between hematologists and obstetricians to address challenges posed by the underlying bone marrow condition and prior treatments.
Considerations for Bone Marrow Donors and Pregnancy
For individuals who have donated bone marrow or peripheral blood stem cells, the donation process typically does not have long-term effects on fertility or future pregnancy success. Medical experts confirm no evidence suggests bone marrow donation impacts a donor’s ability to become pregnant or affects fertility. Donors may experience a temporary recovery period after the procedure, involving fatigue or soreness.
While donation generally poses no lasting fertility issues, active bone marrow or peripheral blood stem cell collection is typically avoided during pregnancy. This guideline protects both the pregnant donor’s health and the developing fetus. However, in specific urgent situations, especially with related donors, hematopoietic progenitor cell collection during pregnancy has been considered. Limited data suggests it can be relatively safe. This highlights that while general guidelines advise against donation during pregnancy, individual circumstances and medical assessment can influence decisions.