synÂ·theÂ·size (sÄ­nâ²thÄ­-sÄ«zâ²) v. synÂ·theÂ·sized, synÂ·theÂ·sizÂ·ing, synÂ·theÂ·sizÂ·es v.tr. 1. To combine so as to form a new, complex product: His works synthesize photography, painting and linguistic devices (Paul Taylor). 2. To form or produce by chemical synthesis. 3. To produce (sound or music) by means of a synthesizer. v.intr. To form a synthesis.
The cause of preterm birth is often not known. Risk factors include diabetes, high blood pressure, being pregnant with more than one baby, being either obese or underweight, a number of vaginal infections, tobacco smoking, and psychological stress, among others.
However, it is not clear when the trigger for PVL occurs--before, during, or after birth. Most babies who develop PVL are premature, especially those born before 30 weeks gestation. Other factors that may be associated with PVL include early rupture of membranes (amniotic sac) and infection inside the uterus.