A study was conducted to assess the association between air particulate pollutants and feto-infant morbidity outcomes across racial/ethnic subgroups. The study population included all singleton live births in Hillsborough County, Florida covering the period from 2000 to 2007. Exposure values for air pollutants of interest were collected for mothers during the time of their pregnancy with available data from air monitors nearest to their homes. From birth certificate data, the primary outcomes of interest were determined including low birth weight, very low birth weight, preterm birth, very preterm birth, and small for gestational age.

Based on the above

(1) What is the study design used?

(2) Is the study observational or experimental?

(3) Is the study descriptive or analytic?

(4) Is the study prospective, retrospective, or cross-sectional?