Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

The natural menstrual cycle revisited – can natural cycle be trusted

Alsbjerg, B. ; Kesmodel, U. S. ; Humaidan, P. and Bungum, L. LU (2024) In Journal of Ovarian Research 17(1).
Abstract

Background: The serum progesterone (P4) level during the luteal phase (LP) plays a crucial role in the initiation and maintenance of pregnancy. However, it is unclear whether the natural cycle consistently provides the best endocrine profile and whether mid-luteal serum P4 levels are always sufficient to support implantation and early pregnancy. The question has become more relevant in relation to fertility treatment, as more frozen embryo transfer cycles are performed in the natural cycle. Moreover, can serum hormone levels and covariates measured during the follicular phase (FP), such as Follicle Stimulation Hormone (FSH), Luteinizing Hormone (LH), Estradiol (E2), Anti-Mullerian Hormone (AMH) and Antral Follicle Count (AFC), be used... (More)

Background: The serum progesterone (P4) level during the luteal phase (LP) plays a crucial role in the initiation and maintenance of pregnancy. However, it is unclear whether the natural cycle consistently provides the best endocrine profile and whether mid-luteal serum P4 levels are always sufficient to support implantation and early pregnancy. The question has become more relevant in relation to fertility treatment, as more frozen embryo transfer cycles are performed in the natural cycle. Moreover, can serum hormone levels and covariates measured during the follicular phase (FP), such as Follicle Stimulation Hormone (FSH), Luteinizing Hormone (LH), Estradiol (E2), Anti-Mullerian Hormone (AMH) and Antral Follicle Count (AFC), be used to predict P4 levels during the luteal phase (LP)? Results: This observational prospective cohort study analysed 26 healthy women with a cycle length between 21–35 days and a body mass index (BMI) < 30 kg/m2. Blood sampling started on the fifth day of the menstrual cycle and continued every fifth day until the next cycle. The procedure was repeated for a total of three cycles. The study found that only ten women had a P4 level greater than 30 nmol/L on cycle day 20 or 25 in all three cycles. In total, only 45 cycles out of 77 cycles had serum P4 levels ≥ 30 nmol/L. The E2 level ≥ 345 pmol/L on cycle day 10 proved to be predictive of a P4 level of ≥ 30 nmol/L on either day 20 or day 25 with a sensitivity of 57% and a specificity of 89%. No other covariates, including the FSH level cycle day 5, LH levels during the follicular phase, age, weight, AFC and AMH cycle day 5 correlated with LP P4 levels. Conclusions: A significant correlation between FP E2 levels cycle day 5 (> 131pmol/L) and cycle day 10 (> 345pmol/L) and a LP P4 level ≥ 30 nmol/l was found; thus, the FP E2 level is a predictor of corpus luteum competence. Our findings highlight the existence of suboptimal P4 levels during the LP and a significant inter-individual and intra-cycle variation in P4 levels during the LP in regular menstruating women.

(Less)
Please use this url to cite or link to this publication:
author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Estradiol, Luteal phase, Natural cycle, Progesterone, Regular menstrual
in
Journal of Ovarian Research
volume
17
issue
1
article number
153
publisher
BioMed Central (BMC)
external identifiers
  • pmid:39039530
  • scopus:85199182960
ISSN
1757-2215
DOI
10.1186/s13048-024-01469-2
language
English
LU publication?
yes
id
c27014eb-de9c-48fc-bb66-5ea83c8a3383
date added to LUP
2024-08-26 15:51:24
date last changed
2024-08-27 03:00:08
@article{c27014eb-de9c-48fc-bb66-5ea83c8a3383,
  abstract     = {{<p>Background: The serum progesterone (P4) level during the luteal phase (LP) plays a crucial role in the initiation and maintenance of pregnancy. However, it is unclear whether the natural cycle consistently provides the best endocrine profile and whether mid-luteal serum P4 levels are always sufficient to support implantation and early pregnancy. The question has become more relevant in relation to fertility treatment, as more frozen embryo transfer cycles are performed in the natural cycle. Moreover, can serum hormone levels and covariates measured during the follicular phase (FP), such as Follicle Stimulation Hormone (FSH), Luteinizing Hormone (LH), Estradiol (E2), Anti-Mullerian Hormone (AMH) and Antral Follicle Count (AFC), be used to predict P4 levels during the luteal phase (LP)? Results: This observational prospective cohort study analysed 26 healthy women with a cycle length between 21–35 days and a body mass index (BMI) &lt; 30 kg/m<sup>2</sup>. Blood sampling started on the fifth day of the menstrual cycle and continued every fifth day until the next cycle. The procedure was repeated for a total of three cycles. The study found that only ten women had a P4 level greater than 30 nmol/L on cycle day 20 or 25 in all three cycles. In total, only 45 cycles out of 77 cycles had serum P4 levels ≥ 30 nmol/L. The E2 level ≥ 345 pmol/L on cycle day 10 proved to be predictive of a P4 level of ≥ 30 nmol/L on either day 20 or day 25 with a sensitivity of 57% and a specificity of 89%. No other covariates, including the FSH level cycle day 5, LH levels during the follicular phase, age, weight, AFC and AMH cycle day 5 correlated with LP P4 levels. Conclusions: A significant correlation between FP E2 levels cycle day 5 (&gt; 131pmol/L) and cycle day 10 (&gt; 345pmol/L) and a LP P4 level ≥ 30 nmol/l was found; thus, the FP E2 level is a predictor of corpus luteum competence. Our findings highlight the existence of suboptimal P4 levels during the LP and a significant inter-individual and intra-cycle variation in P4 levels during the LP in regular menstruating women.</p>}},
  author       = {{Alsbjerg, B. and Kesmodel, U. S. and Humaidan, P. and Bungum, L.}},
  issn         = {{1757-2215}},
  keywords     = {{Estradiol; Luteal phase; Natural cycle; Progesterone; Regular menstrual}},
  language     = {{eng}},
  number       = {{1}},
  publisher    = {{BioMed Central (BMC)}},
  series       = {{Journal of Ovarian Research}},
  title        = {{The natural menstrual cycle revisited – can natural cycle be trusted}},
  url          = {{http://dx.doi.org/10.1186/s13048-024-01469-2}},
  doi          = {{10.1186/s13048-024-01469-2}},
  volume       = {{17}},
  year         = {{2024}},
}