The state of health care is reflected by perinatal and neonatal morbidity and mortality as well as by the frequencies of long-term neurologic and developmental disorders. Many factors, some without immediately rec ognizable significance to childbearing and many still unknown, undoubt edly contribute beneficially or adversely to the outcome of pregnancy. Knowledge concerning the impact of such factors on the fetus and sur viving infant is critical. Confounding analyses of pregnancy outcome, especially these past two or three decades, are the effects of newly un dertaken invasive or inactive...