Use of the Home Ovarian Monitor in pregnancy avoidance

Am J Obstet Gynecol. 1991 Dec;165(6 Pt 2):2008-11. doi: 10.1016/s0002-9378(11)90568-7.

Abstract

The application of the Home Ovarian Hormone Monitor to the avoidance of pregnancy by periodic abstinence has been explored. No woman had difficulty with the daily urine testing, and their results consistently identified the distinctive hormone pattern of the ovulatory cycle and the day of ovulation and correlated closely with the mucus symptoms. The tests gave 4 days or more warning of ovulation in 99% of cycles and allowed intercourse to be resumed 1 to 3 days after ovulation in 88%, giving a mean period of abstinence of 7 days. No pregnancy occurred from intercourse during the late safe days defined by the Monitor, but some early-day pregnancies occurred through long sperm survivals of 6 to 8 days, mostly during the return of fertility after breastfeeding. Rules for the avoidance of pregnancy, with the minimum of testing on the basis of these results, are given.

PIP: This article reports on the results on a 3 year study of 37 Australian women who used the Ovarian Monitor for measuring estrone glucuronide (EIG) and pregnanediol glucuronide (PdG) to avoid pregnancy. The 1st rise in EIG is the equivalent to the rise in basal body temperature and signals the onset of abstention. The EIG fall and PdG rise signals the beginning of the resumption of a nonovulatory period. For breastfeeding women and women with long cycles, the rules change slightly. The result of over the 661 months or the 55 person years show that there is a close correlation between the 1st day of EIG rise and the 1st day of mucus production; there is also close correspondence between laboratory measurement of estrogen values and mucus observations. For breastfeeding women with early ovulatory cycles the results show that ovulation occurred on the day of the EIG fall after the preovulatory peak. The figures indicate that there is a warning of 3-4 days in the EIG rise, and daily monitoring cannot be more precise than 12 hours. The PdG cutoff occurred on days 1,2, or 3 after ovulation. The authors point out that the important points are that 1) the PdG cutoff and protection from pregnancy occur frequently on the day after ovulation, 2) the results reinforce that the test reliably distinguished fertility from infertility, and 3) the median length of abstinence required by the Monitor was 7 days. Throughout the 661 months, only 4 pregnancies resulted, or a rate of 8/100 woman years. For couples who did not report infertility, the conception rate for intercourse within the fertile period by the Monitor measure was nearly 70% compared to the expected figure of 25%/cycle. With a 5 day usual sperm survival, the last day of the EIG baseline is still a concern, since most unplanned pregnancies occurred on this day. Also, women are highly fertile on the 2nd and 3rd ovulatory cycles after 10 months or more of breastfeeding. The population was 30 years with 3 or more children and had completed families. Most considered the test a nuisance. 62% had sexual intercourse during the early safe days and all used the later safe days. 21 used late safe days just after the PdG cutoff was reached and 13 added several days for safety reasons. Remembering times of urination was sometimes a problem. Difficulties were experienced in scheduling the time of measurements.

MeSH terms

  • Adult
  • Contraception*
  • Estrone / analogs & derivatives
  • Estrone / urine
  • Female
  • Humans
  • Ovulation / physiology
  • Ovulation Detection*
  • Pregnanediol / analogs & derivatives
  • Pregnanediol / urine
  • Reagent Kits, Diagnostic
  • Self Care

Substances

  • Reagent Kits, Diagnostic
  • pregnanediol-3 alpha-glucuronide
  • estrone-3-glucuronide
  • Estrone
  • Pregnanediol