title: Implications of subdividing marital status: are unmarried mothers with partners different from unmarried mothers without partners? An exploratory analysis.
abstract: OBJECTIVE
  To determine the analytic advantages obtained from separating unmarried mothers with partners from unmarried mothers without partners when assessing risk of adverse birth outcomes.
  
  
  METHODS
  Data were obtained from Listening to Mothers II, a national survey of women's childbearing experiences. Marital status was asked with three choices: married (71%), unmarried with partner (24%), and unmarried without partner (5%). Demographic differences between the three marital status groups were compared using chi (2) tests. Multiple logistic regressions, controlling for age, education, race/ethnicity, and parity, tested for associations between birth outcomes (birth weight and gestational age) and marital status.
  
  
  RESULTS
  Unmarried mothers with partners and without partners were similar in age, education, and parity. Unmarried mothers without partners delivered by cesarean more often (39%) and were more likely to have a doctor as birth attendant (99%) than unmarried mothers with partners. The multiple logistic regressions indicated that, compared to married mothers, unmarried mothers with partners had the same risk of premature infants, while unmarried mothers without partners had greater risk. Unmarried first-time mothers with partners had over twice the risk of premature infants (OR = 2.71; 1.07-6.85) and unmarried mothers without partners had over 5 times the risk (OR = 5.64; 1.68-18.92) when compared to married first-time mothers.
  
  
  CONCLUSIONS
  Mothers without partners were at higher risk than unmarried mothers with partners indicating a gradient of risk. Future data collection on marital status should consider distinguishing between unmarried mothers with and without partners.
authors.affiliation: Department of Biostatistics, Boston University School of Public Health, Boston, MA 02118, USA. ryoung@bu.edu
authors.forename: Robin L
authors.initials: RL
authors.lastname: Young
authors.forename: Eugene
authors.initials: E
authors.lastname: Declercq
mesh_terms: D000293:Adolescent; D000328:Adult; D003625:Data Collection; D005260:Female; D006801:Humans; D007086:Illegitimacy; D017533:Marital Status; D008875:Middle Aged; D011247:Pregnancy; D011256:Pregnancy Outcome; D012107:Research Design; D018570:Risk Assessment / Q000379:methods; D012747:Sexual Partners; D014481:United States; D055815:Young Adult