Pregnancy chance peaked on the mucus Peak Day in a Creighton cohort
In this cohort, couples charting with the CREIGHTON MODEL FertilityCare System had their highest estimated pregnancy chance on the Peak Day. A retrospective cohort followed 309 normally fertile couples and 117 couples with trouble getting pregnant. The estimated chance was 38 out of 100 in the first group, 14 out of 100 in the second.
Key Findings
Analysis covered 1681 cycles with 81 pregnancies from 309 normally fertile couples, and 373 cycles with 30 pregnancies from 117 couples with trouble getting pregnant.
Daily fecundity was highest on the Peak Day, at 0.38 in normally fertile couples and 0.14 in the group with trouble getting pregnant.
Daily fecundity stayed above 0.05 for 6 days in normally fertile couples (day -3 to day +2) and for 3 days in the other group (day -1 to day +1).
In normally fertile couples, a higher Mucus Cycle Score went with higher cycle fecundity. The other group showed no such relationship.
Cycle fecundity varied widely among normally fertile couples: above 85 percent at the 95th percentile, below 5 percent at the 5th.
Interpretation
Couples charting with the Creighton Model get a clear picture of the fertile window from these day-by-day odds. Pregnancy chance rises in the days before the Peak Day. The chance drops within two days after the Peak Day. In couples with trouble getting pregnant, the chance per cycle is lower. The fertile window still runs from one day before the Peak Day through one day after. Charting still finds the window. A higher Mucus Cycle Score went with higher fecundity in normally fertile couples. The score points to mucus quality as a marker of the fertile window. The findings support larger studies of the score in couples with reduced fertility.
RRM Context
The findings also appeared in Obstetrics & Gynecology in 2003. Fertility awareness-based methods work by finding the fertile window before ovulation. The cohort gives day-by-day pregnancy odds from standardized mucus charting. A higher Mucus Cycle Score tracked with fecundity in normally fertile couples. The score did not track with fecundity in the group with trouble getting pregnant.
Our editorial summary of this paper, not the article's abstract.
Abstract
This chapter reports the CREIGHTON MODEL Multicenter Fecundity Study, a retrospective cohort study of new CrMS users at six centers in the United States that estimated the probability of conception by day of the cycle and by mucus cycle score. Among 309 normally fertile couples and 117 subfertile couples, the highest daily fecundity fell on the Peak Day, at 0.38 for normally fertile couples and 0.14 for subfertile couples. The mucus cycle score showed a near linear positive relationship with cycle fecundity among normally fertile couples, and the study did not find that relationship among subfertile couples. The authors also report wide variability in fecundity between couples and discuss limitations, including uncertain fertility status in the subfertile group, charts that could not be obtained and the lack of an independent marker of ovulation.
03r0ha626 