What is the effect of oestrogen and progesterone at the beginning of the menstrual cycle in delaying entry into the fertile window?
Summary Answer
Both oestrogen and progesterone contribute to a delay in the onset of the fertile window.
What Is Known Already
Oestrogen enhances cervical mucus secretion while progesterone inhibits it.
Study Design, Size, Duration
Observational study. Daily observation of 220 menstrual cycles contributed by 88 women with no known menstrual cycle disorder.
Participants/Materials, Setting, Methods
Women recorded cervical mucus daily and collected first-morning urine samples for analysis of oestrone-3-glucuronide, pregnanediol-3-alpha-glucuronide (PDG), FHS, and LH. They underwent serial ovarian ultrasound examinations. The main outcome measure was the timing within the cycle of the onset of the fertile window, as identified by the appearance of mucus felt or seen at the vulva. MAIN RESULTS AND THE ROLE OF CHANCE: Low oestrogen secretion and persistent progesterone secretion during the first week of the menstrual cycle both negatively affect mucus secretion. Doubling oestrogen approximately doubled the odds of entering the fertile window (OR: 1.82 95% CI=1.23; 2.69). Increasing PDG from below 1.5 to 4 µg/mg creatinine was associated with a 2-fold decrease in the odds of entering the fertile window (OR: 0.51 95% CI=0.31; 0.82). Prolonged progesterone secretion during the first week of the menstrual cycle was also statistically significantly associated with higher LH secretion. Finally, the later onset of the fertile window was associated with statistically significant persistently elevated LH secretion during the luteal phase of the previous menstrual cycle.
Limitations, Reasons for Caution
This post hoc study was conducted to assess the potential impact of residual progesterone secretion at the beginning of the menstrual cycle. It was conducted on an existing data set because of the scarcity of data available to answer the question. Analysis with other datasets with similar hormone results would be useful to confirm these findings.
Wider Implications of the Findings
This study provides evidence for residual progesterone secretion in the early latency phase of some menstrual cycles, which may delay the onset of the fertile window. This progesterone secretion may be supported by subtly increased LH secretion during the few days before and after the onset of menses, which may relate to follicular waves in the luteal phase. Persistent progesterone secretion should be considered in predicting the onset of the fertile window and in assessing ovulatory dysfunction. STUDY FUNDING/COMPETING INTEREST(S): The authors declare no conflicts of interest. No funding was provided for this secondary data analysis.
Self-reported dietary intake varies across menstrual cycle phases, but objective assessments of dietary intake together with appetite and resting metabolic rate (RMR) are limited. This study aimed to assess differences in dietary intake, appetite, and RMR during two hormonally-distinct menstrual cycle phases in laboratory and free-living settings. Healthy premenopausal females with predictable normal-length menstrual cycles completed two study visits: one in the late-follicular and one in the mid-luteal phase. Menstrual cycle phases were assessed using urinary luteinizing hormone surge and prospective cycle days. Participants consumed a 2-day energyand macronutrient-balanced run-in diet prior to each visit. RMR was measured with indirect calorimetry, followed by appetite ratings before and after a standardized breakfast, and a food cravings questionnaire. Appetite was also tracked for 2.5 days post-visit in a free-living environment. Ad libitum energy and macronutrient intakes were measured using pre-weighed plus weighing of uneaten food at an in-laboratory lunch meal, as well as during the 2.5-day free-living period. Eighteen participants were included (age: 21 ± 4 years; body mass index: 21.2 ± 1.5 kg/m2). There were no differences between in-laboratory ad libitum energy or macronutrient intakes, appetite, or food cravings between phases. RMR did not differ between phases, although the mid-luteal phase RMR tended to be higher (104 ± 218 kcal/day higher; P = 0.074). No main or interaction effects for phase or time were observed for free-living dietary intake nor appetite ratings. Although RMR tended to be increased during the luteal phase, comprehensive appetite and energy intake assessments showed no significant cycle-phase differences in these 18 participants.
Self-reported dietary intake varies across menstrual cycle phases, but objective assessments of dietary intake together with appetite and resting metabolic rate (RMR) are limited. This study aimed to assess differences in appetite, dietary intake, and RMR during two hormonally-distinct menstrual cycle phases in laboratory and free-living settings. Healthy premenopausal females with predictable normal-length menstrual cycles completed two study visits: one in the late-follicular and one in the mid-luteal phase. Menstrual cycle phases were identified using urinary luteinizing hormone surge and cycle days. Participants consumed a 2-day energy- and macronutrient-balanced run-in diet prior to each visit. RMR was measured with indirect calorimetry, followed by appetite ratings before and after a standardized breakfast, and completed a food cravings questionnaire. Appetite was also tracked for 2.5 days post-visit in a free-living environment. Ad libitum energy and macronutrient intake were measured using pre-weighed plus weighing of uneaten food at an in-laboratory lunch meal, as well as during the 2.5-day free-living period. Eighteen participants were included (age: 21±4 years; body mass index: 21.2±1.5 kg/m 2 ). There were no differences between in-laboratory ad libitum energy or macronutrient intakes, appetite, or food cravings between phases. RMR did not differ between phases, although the mid-luteal phase RMR trended toward higher (104±218 kcal/day higher ; P =0.074). No main nor interaction effects for phase and time were observed for free-living dietary intake nor appetite ratings. Accurate measurements show no differences in appetite or energy intake between menstrual cycle phases, though RMR may be slightly elevated in the luteal phase.
Prior JC, 2022·The Cambridge Handbook of Evolutionary Perspectives on Sexual Psychology·
Periodic vaginal bleeding occurs in humans (who are henceforth called “women,” a word describing culture as well as biology), old-world apes, and few other mammals. By current concepts, women’s menstrual cycles provide estrogen for thirty to fifty years; following one year of no flow they become menopausal and “estrogen deficient.” By contrast we now know that the purpose of menstrual cycles is to supply all cells and tissues with the balanced essential actions of estradiol (E2) and progesterone (P4) produced in feedback-controlled patterns to facilitate fecundability and preserve younger women’s well-being. We also now know that menopausal women’s health is negatively affected (by increased osteoporosis, heart disease, breast and endometrial cancers) if those past menstrual cycles produced inadequate net P4 to counterbalance and complement E2’s actions. Menstrual periodicity, flow, and ovulatory characteristics in women reflect the integrated actions/interactions of the central nervous system through the hypothalamus and pituitary, ideally leading to each cycle’s stimulation of a dominant egg-containing follicle. That follicle, by central complex feedback loops, produces the cyclic, graded amounts of estradiol (E2) and progesterone (P4) for that threeto five-week period and releases a viable egg. Central reproductive connections allow adult premenopausal women’s menstrual cycle periodicity, ovulation or not, and luteal phase lengths, that can be adapted to the challenges and demands of each woman’s current physiological and sociocultural/emotional environments. These new ideas are based on the differing and complementary cellular and tissue actions of E2 and P4. E2 is essential for cell growth and stimulates cell proliferation. P4 uniquely counterbalances and controls proliferation while stimulating cell differentiation and tissue maturation. Thus, E2–P4 actual and relative productions integrate cycles within each woman’s reproductive lifecycle (adolescent, premenopausal, perimenopausal), and are related to her nutrition, illness, energy expenditure, and social/emotional/spiritual environments. The subtlest indication of a stressed reproductive system is truncated P4 production in the short luteal phase within a normal-length, ovulatory menstrual cycle. This adaptation protects a woman from pregnancy when she has inadequate net energy balance or is under emotional/social/spiritual or physical duress. Thus, a normal luteal phase length within a threeto five-week regular menstrual cycle is a bellwether of women’s well-being. By contrast, regular cycles with ovulatory disturbances (anovulation or short luteal phases; E2>P4) predict current decreased well-being and poor later life health. The purpose of this review is to provide a practical approach to understanding this new women’s menstrual cycle balanced E2–P4 paradigm applied to common clinical situations including subfertility with regular cycles, premenstrual symptoms, and heavy menstrual flow.