Twin Pregnancy: a Challenge for Patients, Families and Health Professionals

Twin pregnancies represent 3-4% of all births and in the last two decades the rate of twin pregnancies has steadily increased, essentially due to the spread of assisted fertilization techniques, the use of drugs that stimulate ovulation and increase in maternal age at conception. Multiple pregnancies pose unique challenges for the patient, families, caregivers and society. Indeed, twin pregnancy is associated with an increased risk compared with singleton pregnancies of all feto-maternal complications of pregnancy (Level of Evidence II-2). In twin pregnancies (both monochorionic, MC, and bichorionic, BC) the incidence of preeclampsia is about 10%, 3 times higher than in singleton pregnancies. In singleton pregnancy, the mean gestational age (GE) at delivery is 39 weeks, the mean GA at delivery in twin pregnancies is less than 36 weeks, reflecting a 9-fold higher prevalence of spontaneous preterm delivery than in singleton pregnancy. Gestational diabetes complicates about 22% of twin pregnancies compared to 7-11% of singleton pregnancies. Twin pregnancy, compared to single pregnancy, has an increased incidence of perinatal and neonatal mortality, low birth weight, chromosomal or structural defects. A key factor to know is chorionicity. Chorionicity is a key data to acquire in the first trimester. Indeed, some complications of twin pregnancy are specific to MC pregnancy. About 20-33% of twins share the same placenta and it is precisely in these cases that a condition of greater risk is created. The most common complications of MC pregnancy are: twin-to-twin transfusion syndrome (TTTS), due to the presence of vascular anastomoses at the level of the placenta and a clear imbalance in blood flow between the twins; selective intrauterine growth restriction; the anemia-polycythemia sequence (TAPS); twin reversed arterial perfusion (TRAPS). Thus, the MC twin pregnancy is at increased risk of feto-maternal complications. The complications of twin pregnancy place a heavy