Preterm birth occurs before 37 weeks gestation. Extremely early is less than 28 weeks, very early 28-32 weeks. Late preterm birth occurs between 34-36 weeks
PDA occurs when ductus arteriosus fails to close after birth. Allows oxygenated blood to flow from aorta to pulmonary artery. Common in premature newborns, affecting 20-60% of premature births. Occurs in 1 in 2,000 full-term births
Fetal membranes include amnion, chorion, allantois, and yolk sac. Amnion and chorion form chorioamniotic sac surrounding embryo. Membranes develop from trophoblast layer of blastocyst. Amnion is avascular, chorion contains fetal blood vessels
Infant mortality is death of infants under one year per 1,000 live births. Global under-five mortality rate dropped from 22.5% in 1950 to 4.5% in 2015. Infant mortality rate declined from 65 to 29 deaths per 1,000 live births
PVL is white matter brain injury near lateral ventricles. Most common in premature infants weighing less than 1500g. Occurs when blood/oxygen flow to periventricular region is decreased. Damaged blood-brain barrier triggers inflammatory response
Preterm birth occurs before 37 weeks of pregnancy. 13.4 million babies were born prematurely in 2020. Approximately 900,000 children died from preterm birth complications in 2019