“…Nevertheless, there are a growing number of contemporary studies that have evaluated potential links between air pollution and birth weight, [445][446][447][448][449][450][451][452][453][454][455][456] premature birth, 449,456 -458 fetal growth, 459 -461 intrauterine mortality, 462 birth defects, 463 and lymphocyte immunophenotypes in cord and maternal blood at delivery. 464 Recent reviews of the literature dealing with air pollution and these various birth outcomes 441,442,444 generally suggest that there may be effects of ambient PM air pollution on these outcomes but that these effects are not well understood. Although the evidence is reasonably compelling that PM exposure increases the risk of infant mortality, especially postneonatal respiratory mortality, there remain serious gaps in our knowledge regarding the potential effects of ambient PM on fetal growth, premature birth, and related birth outcomes.…”