Prospective study of time to pregnancy and adverse birth outcomes

In this registry-based cohort study, we found positive associations between prospectively measured time to pregnancy and several adverse birth outcomes, including preterm birth, low birth weight, placental disorders, gestational diabetes, and cesarean section.

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Lauren A. Wise, Sc.D., Ellen M. Mikkelsen, Ph.D., Henrik Toft Sørensen, M.D., Dr.P.H., Kenneth J. Rothman, Dr.P.H., Kristen A. Hahn, M.P.H., Anders H. Riis, M.S., Elizabeth E. Hatch, Ph.D.

Volume 103, Issue 4, Pages 1065-1073



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


Prospective cohort study.


Not applicable.


A total of 3,521 singletons born to women aged 18-40 years at cohort entry.



Main Outcome Measure(s):

Selected birth outcomes, including preterm birth (PTB,


Multivariable RRs for PTB in relation to TTP of 3–5, 6–11, and ≥12 vs.


In a prospective cohort study of Danish pregnancy planners, delayed conception was a marker for adverse birth outcomes, after accounting for fertility treatment.

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Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

Fertility and Sterility® is an international journal for obstetricians, gynecologists, reproductive endocrinologists, urologists, basic scientists and others who treat and investigate problems of infertility and human reproductive disorders.