Menstrual Characteristics Associated With Successful Pregnancy Within 6 Months Among Women Planning to Conceive.

Background: Enhanced awareness/understanding of menstrual cycle characteristics and the ovulation period can help raise the rate of natural conception among women planning to conceive. The multidimensional nature of menstrual characteristics and their relationship with conception have been rarely addressed in the literature.

Purpose: This study describes five menstrual cycle characteristics and explores their association with conception and time to pregnancy (TTP).

Methods: This prospective longitudinal study was conducted between August 2018 and September 2019, with a total of 289 women participating. All of the participants were planning to become pregnant and were interviewed in person during the baseline examination. Menstrual cycle characteristics were recorded from the time participants joined the study through a minimum of three subsequent cycles. Five cycle characteristics were recorded, including overall length, number of days of bleeding, signs of ovulation, occurrence of dysmenorrhea, and occurrence of blood clots. Signs of ovulation were defined as a drop in basal body temperature lasting 1-2 days accompanied by a positive ovulation test result. Pregnancy outcomes and TTP were recorded over the first 6 months after enrollment as a participant in this study.

Results: Nearly half (44.6%) of the participants became pregnant during the 6-month observation period, and the mean TTP of the sample was 81.9 (SD=38.1) days. Based on the 1,321 menstrual cycles recorded in this study, the Cox proportional hazards regression results identified participants aged 30-35 years as more likely to become pregnant than those under 30. Having a menstrual cycle length of 27-32 days, bleeding for 5-6 days, signs of ovulation on Days 13-16, and lack of dysmenorrhea or blood clots in the menstrual period were identified as predictors of pregnancy.

Conclusions/implications for practice: Health care providers should assist women planning to conceive in monitoring their menstrual cycles and devising strategies to optimize them, reduce dysmenorrhea and blood clots, and use ovulation test strips to enhance natural conceptions.