Influence of cycle variability and coital frequency on the risk of pregnancy
Steiner, M.J.; Hertz-Picciotto, I.; Raymond, E.; Trussell, J.; Wheeless, A.; Schoenbach, V.
Contraception 60(3): 137-143
1999
ISSN/ISBN: 0010-7824 PMID: 10640156 DOI: 10.1016/s0010-7824(99)00073-6Document Number: 524961
This article highlights the influence of cycle variability and coital frequency on the risk of pregnancy using data from the completed female condom trial. Daily diaries of women, which include coital frequency and menstrual cycle, were reanalyzed to evaluate the factors that affect the probability of pregnancy. A higher probability of pregnancy was reported among noncompliant women, women with less variable menstrual cycles, and women engaging in frequent intercourse during a 6-month trial. The adjusted hazard ratios and 95% confidence intervals for these three covariates were 6.1 and 2.0-18.7 (noncompliant women), 7.2 and 1.0-54.3 (less variable menstrual cycles), and 2.0 and 0.7-5.3 (frequent intercourse), respectively. The overall pregnancy rate obtained in this study represent average effects for a population with the particular mix of characteristics. This study appears to demonstrate a much lower risk of pregnancy for women with menstrual cycles outside the range of 17-43 days.