Recent use of oral contraceptives and menstrual cycle characteristics


Najmabadi S [1], Stanford JB [1]

[1] Office of Cooperative Reproductive Health, Division of Public Health, Department of Family and Preventive Medicine, University of Utah, Salt Lake City, UT, USA.


Oral contraceptives (OC) are the most common temporary contraception used in the USA. We assessed menstrual cycle characteristics in relation to recent use of OC.

We studied 3,096 menstrual cycles of 521 women with no known subfertility, who were followed for up to 1 year. Women recorded vaginal bleeding or cervical mucus discharge daily. We used the peak day of cervical mucus as the estimated day of ovulation and the last day of the follicular phase. We used generalized linear mixed models to describe menstrual cycle parameters among 191 recent OC users (OCU) (1,067 cycles) who discontinued OC within the year before joining the study, compared to 330 women (2,029 cycles) who did not use OC (NOC).

Majority of women were 35 days 1.52, CI: 1.03, 2.23]; longer follicular phase [20.3 days, CI: 19.3, 21.2 vs 18.1 days, CI: 17.4, 18.8, OR follicular phase >21 days 1.75, CI: 1.32, 2.32]; shorter luteal phase (11.1 days, CI: 10.7, 11.5 vs 11.8 days, CI: 11.5, 12.1, OR luteal phase <8 days 2.43, CI 1.69, 3.50]; shorter menses [6.1 days, CI: 5.9, 6.3 vs 6.4 days, CI: 6.2, 6.5]; and lower mucus quality [7.6, CI: 7.0, 8.1 vs 8.7, CI: 8.4, 9.1]. Women who discontinued pills within 60 days prior to the study compared to those who discontinued pills earlier had the most deviation from cycle parameters of NOCs.

Conclusions: Our findings indicate reduced fecundability for some months after discontinuation of pills. The time needed to gain normal menstrual function needs further assessment.

North American Regional Conference for Restorative Reproductive Medicine.  July 21, 2020. 


Shahpar Najmabadi. PhD University of Utah, Department of Family and Preventive Medicine, Salt Lake City, USA. 

Dr. Shahpar Najmabadi received Masters of Science in Midwifery from the Shahid Beheshti University of Medical Sciences in Tehran. She earned her Masters of Public Health at the University of Utah at 2012 with a Certificate in Global Health  and continued on to obtain a PhD in Public Health at 2019.

She received a Certificate in Women Health in 2016.  Dr. Najmabadi previously worked as a research analyst for the University of Utah, Division of Public health, a consultant for the National Committee for Quality Assurance in Washington, DC in 2016, and a research analyst in the Office of Cooperative Reproductive Health at the University of Utah.  Currently, she works as a Post-Doc Research Associate in the Department of Family and Preventive Medicine at the University of Utah.


North American Regional Conference for Restorative Reproductive Medicine.  July 22, 2020.