Outcomes
Maternal and pregnancy outcomes examined included gestational diabetes mellitus (GDM), preeclampsia or HELLP syndrome (hemolysis, elevated liver enzymes and low platelets syndrome), intrauterine death (IUD) of at least one twin, cesarean or vaginal delivery, wound healing disorders, postpartum hemorrhage (PPH), including those in need of blood transfusions, uterine atony with the necessity of Sulprostone or a tamponade, and preterm birth.
GDM was diagnosed according to the guidelines of the American Diabetes Association. Every gravida underwent a 75 g oral glucose tolerance test between 24 and 28 weeks of gestation. GDM was diagnosed when at least one limiting value was exceeded (fasting: 92 mg/dL, 1 hour: 180 mg/dL, 2 hours: 153 mg/dL). Preeclampsia was defined according to the Practice Bulletin of the American College of Obstetricians and Gynecologists (ACOG) as a blood pressure of ≥140/90 mmHg and proteinuria or at least one sign of organ damage. IUD was defined according to the Royal College of Obstetricians & Gynaecologists as missing signs of life in utero after 24 completed weeks of gestation. PPH was defined as bleeding >1,000 ml or blood loss with signs of hypovolemia within 24 hours after birth. Gestational age was calculated through measurement of the fetal crown-rump length using ultrasound and categorized into groups of ≤27+6, 28 – 31+6 and 32 – 36+6 weeks of gestation.
Neonatal outcomes analyzed were birth weight discordance between twins, admission to the neonatal intensive care unit (NICU), pH of the umbilical artery and an APGAR score value below seven after five minutes.
Birth weight discordance was defined according to Practice Bulletin of the ACOG, estimated for every neonate, and classified into three groups of <20%, 20 – 24,9% and ≥25%. Fetuses with a birth weight discordance above 20% were monitored more intensively. Admission to NICU was defined as admission of at least one twin. The arterial umbilical pH was subdivided into categories of ≤7.0, 7.01 – 7.1 and 7.11 – 7.2.