Are pregnancy planning and timing associated with preterm or small for gestational age births?

OBJECTIVE: To investigate whether unplanned or poorly timed pregnancies (self-reported at enrollment) are associated with preterm or small for gestational age births.
DESIGN: Prospective cohort study.
SETTING: Not applicable. PATIENT(S): Two thousand six hundred fifty-four pregnant women <18 weeks estimated gestational age with a singleton pregnancy. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Preterm and small for gestational age births. RESULT(S): In adjusted analyses, pregnancy planning was not statistically significantly associated with preterm (odds ratio [OR] 1.18; 95% confidence interval [CI], 0.85-1.65) or small for gestational age birth (OR 1.17; 95% CI, 0.69-1.97). Similarly, poorly timed pregnancies were not statistically significantly associated with preterm (OR 0.85; 95% CI, 0.53-1.38) or small for gestational age birth (OR 0.92; 95% CI, 0.65-1.29). Combining pregnancy planning (yes/no) and timing (yes/no) into a 4-level category showed no statistically significant association with preterm birth or small for gestational age. CONCLUSION(S): In a large cohort with antenatally assessed pregnancy planning and timing, outcome data collected from medical record abstraction, and robust analysis adjusting for multiple confounding factors including maternal demographics, medical conditions, and other risk factors, neither pregnancy planning nor pregnancy timing showed a statistically significant association with preterm or small for gestational age infants. This study improves upon previous analyses that lacked adjustment for confounding and used retrospective self-reporting to assess pregnancy planning and timing, and preterm and small for gestational age births. Findings may differ in higher risk populations with higher prevalence of preterm or small for gestational age births.