Risk of obstetrical complications in organ transplant recipient pregnancies

Pregnancy after kidney and liver transplantation is becoming relatively common, although, in both groups, maternal complications are higher than in the general population. Both mean gestational age and mean birthweight seems significantly greater for liver transplant versus kidney transplant recipients and the risk of hypertension during pregnancy seems also lower for liver transplant than kidney transplant recipients. Thus, sequelae of chronic kidney diseases have stronger adverse effects on pregnancy, leading to a higher occurrence of adverse neonatal complications. Also, gestation in heart recipients may be complicated and preeclampsia seems to occur more frequently. However, the transplanted heart seems to adapt well to changes caused by pregnancy, such as increased cardiac workload and output, and elevated maternal oxygen consumption. More problematic is pregnancy in lung transplant recipients. Spontaneous pregnancy and healthy childbirth after bone marrow grafting is relatively rare due to irradiation, but, if gestation occurs, no specific problems have been identified. Obstetrical syndromes associated with transplantation reflect the pathology of defective deep placentation, where conversion of uterine spiral arteries remains largely restricted to the decidual segment. The myometrial segments of the uteroplacental arteries have a unique vascular memory and are at great risk to develop obstructive, atherosclerotic lesions. A similar increased risk of complications already existed in pregnancies during the years before transplantation. The effect of immunosuppressive therapy remains speculative. Therefore, the main target for improving the outcome of pregnancy in women at risk is the strict antihypertensive treatment from the earliest stage of pregnancy.