TOPICS: Maternal quadruple screen, beta-hCG, estriol, inhibin A, yolk sac, alpha fetoprotein (AFP), parturition, delivery, pre-labor, labor, false labor, Braxton-Hick contractions, estrogen:progesterone ratio, uterine stretching, fetal stress, contractions, trisomy 13, Patau syndrome, trisomy 18, edward syndrome, trisomy 21, down syndrome, prostaglandin, oxytocin, placenta, corpus luteum
