title: Spontaneous preterm birth: a case-control study.
abstract: Information on demographic characteristics, life-style, and reproductive, prenatal, and medical history was obtained from the prenatal records of 140 women with a preterm delivery (cases) and 280 women with a term delivery (controls) matched by age. Compared with controls, a greater proportion of cases were nonwhite, never married, and educated less than 12 years. When logistic regression was used to control for confounding variables, a number of risk factors were found to be associated with an increased risk for preterm delivery: a history of a prior preterm delivery (relative risk, 3.5; confidence interval, 1.6 to 7.8), smoking during the pregnancy (p value test of trends, 0.005), and a prepregnancy weight less than 61.5 kg (relative risk, 2.0; 95% confidence interval, 1.2 to 3.2). Seven (5%) cases and none of the controls indicated a history of maternal diethylstilbestrol exposure (p less than 0.001). A history of prior induced abortion was associated with a modest increase in risk for a spontaneous preterm delivery (relative risk, 1.6; confidence interval, 0.9 to 2.7), and this risk increased with increasing numbers of induced abortions (p value for chi 2 test of trend, 0.02).
authors.affiliation: Obstetrics and Gynecology Epidemiology Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115.
authors.forename: I
authors.initials: I
authors.lastname: de Haas
authors.forename: B L
authors.initials: BL
authors.lastname: Harlow
authors.forename: D W
authors.initials: DW
authors.lastname: Cramer
authors.forename: F D
authors.initials: FD
authors.lastname: Frigoletto
mesh_terms: D000028:Abortion, Induced / Q000009:adverse effects; D000328:Adult; D000367:Age Factors; D001835:Body Weight; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008393:Marriage; D007752:Obstetric Labor, Premature / Q000453:epidemiology*; D011247:Pregnancy; D044469:Racial Groups; D012306:Risk; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D012923:Social Class; D014481:United States