• Article

Prospective study of time to pregnancy and adverse birth outcomes


Wise, L. A., Mikkelsen, E. M., Sorensen, H. T., Rothman, K. J., Hahn, K. A., Riis, A. H., & Hatch, E. E. (2015). Prospective study of time to pregnancy and adverse birth outcomes. Fertility and Sterility, 103(4), 1065-1073.e2. DOI: 10.1016/j.fertnstert.2015.01.024, 10.1016/j.fertnstert.2015.01.024


Objective: To investigate the association between time to pregnancy (TTP) and adverse birth outcomes.

Design: Prospective cohort study.

Setting: Not applicable.

Patient(s): A total of 3,521 singletons born to women aged 18-40 years at cohort entry.

Intervention(s): None.

Main Outcome Measure(s): Selected birth outcomes, including preterm birth (PTB,

Result(s): Multivariable RRs for PTB in relation to TTP of 3-5, 6-11, and >= 12 vs. = 12 vs. = 12 cycles) were associated with increased risks of low birth weight (RR 1.80, 95% CI 0.97-3.35), cesarean delivery (RR 1.64, 95% CI 1.27-2.12), placental disorders (RR 2.21, 95% CI 1.07-4.56), ischemic placental disease (RR 1.56, 95% CI 0.99-2.44), pre-eclampsia (RR 1.45, 95% CI 0.79-2.65), and postpartum hemorrhage (RR 1.58, CI 1.14-2.19), and decreased risks of macrosomia (>= 4,500 g; RR 0.63, 95% CI 0.35-1.13) and large for gestational age (RR 0.76, 95% CI 0.58-1.00). Longer TTP showed little association with small for gestational age.

Conclusion(s): In a prospective cohort study of Danish pregnancy planners, delayed conception was a marker for adverse birth outcomes, after accounting for fertility treatment. (C) 2015 by American Society for Reproductive Medicine.