The different forms of early pregnancy loss (EPL) are: threatened miscarriage, inevitable miscarriage, missed miscarriage and recurrent miscarriage. Gestational trophoblastic disease (GTD) is a term commonly applied to a spectrum of interrelated diseases originating from the placental trophoblast. The main categories of GTD are complete hydatidiform mole, partial hydatidiform mole and choriocarcinoma. Studies have described the outcome of assisted reproductive technology (ART) pregnancies following prenatal diagnosis but there appear to be no cytogenetic data regarding pregnancy loss before 11 weeks of gestation. Molar pregnancies may be complete (diploid and androgenetic usually arising from fertilization by a haploid sperm which doubles its chromosomes and takes over the ovum) or partial (triploid and predominantly genetically male). Progesterone and human chorionic gonadotrophin (HCG) have been used in the diagnosis, management and treatment of abnormal early pregnancy. This chapter discusses management of multiple gestation pregnancy (MGP) after ART, and multifetal pregnancy reduction (MFPR).