How long can luteal phase last

Individualised identification of the fertile window based on BBT and menstruation dates can help to reduce the time to conception in some cases. With women globally delaying fertility 39 the potential value of fertility tracking apps as a platform for delivery of individualised fertility education and preconception care should not be underestimated. Anecdotally there is poor understanding of fertility amongst the general population, which can lead to both unintended pregnancies and delayed time to conception with associated psychological suffering for those wishing to start a family.

The value of fertility apps as educational platforms to achieve public health benefits through standardised health promotion messages during key stages of reproductive life such as preconception, pregnancy and birth spacing is also being explored.

Finally, the widespread use of mobile phone apps for personal health monitoring is generating large amounts of data on the menstrual cycle. Provided that the real-world data can be validated against traditional clinical studies done in controlled settings, there is enormous potential to uncover new scientific discoveries.

This is one of the largest ever analyses of menstrual cycle characteristics. These initial results only scratch the surface of what can be achieved. We hope to stimulate greater interest in this field of research for the benefit of public health. Physiological data, including daily BBT sublingual measurement , cycle by cycle dates of menstruation, and urinary LH test results, were collected prospectively from users of the Natural Cycles app. Participant characteristics including age and BMI were determined through mandatory in-app questions that must be completed during the sign-up process.

Users are recommended to measure their temperature on 5 out of 7 days per week as soon as they wake up. They are requested to report whether a temperature measurement may be deviating for reasons such as disrupted sleep or alcohol consumption the night before. The algorithm also identifies deviating temperatures if the value is outside the range All users in the study had consented at registration to the use of their data for the purposes of scientific research and could remove their consent at any time.

A surge in LH is responsible for triggering follicle rupture. At the onset of menses, marking the start of the follicular phase, the corpus luteum collapses and progesterone levels fall back to a low level until the next preovulatory increase.

Progesterone has a thermogenic effect so its levels can be tracked by measuring BBT. BBT is at a relatively constant low level during the follicular phase, reaching its lowest level the nadir prior to ovulation, 43 and then displays a distinct rise of 0. The algorithm within the app detects ovulation retrospectively based on BBT measurements, menstrual cycle parameters and additionally on positive urinary LH tests. The algorithm can identify the BBT rise associated with ovulation in the presence of measurement errors, missing data and BBT rise occurring over a variable length of time.

The horizontal grey line is the cover line. Comparisons are made using standard statistical techniques taking into account sample size and standard deviation. If ovulation is not detected in this initial test then more tests are performed with a rolling average over an increasing number of days up to 1 week.

If a positive-LH test has been recorded, fewer high temperatures are required in order to detect ovulation since the LH test provides extra confidence that ovulation has occurred. The app recommends which days to take an LH test, considering the uncertainty of the ovulation day such that it minimises the number of LH tests used while ensuring that the user will not miss her surge. For users on Plan mode the app always recommends which days to check for LH since Plan users are in general more keen on finding the surge, even if it requires a large number of LH tests.

The app will, however, only recommend to start checking LH 10 days prior to the earliest recorded ovulation day even if the total uncertainty is larger. As the LH surge typically lasts for several days 42 the probability of missing the surge if only testing every other day is relatively small. The app, therefore, recommends to only test every other day until close to the expected ovulation day.

If one positive LH test has been entered, but no positive or negative LH test entry exists on the day immediately before, then the user is encouraged to test the following day to establish whether the positive test corresponds to the first or second day of the surge.

If no such test is entered, the app assumes the first LH test marks the first day of the surge. Cycles in which ovulation has been detected are hereafter referred to as ovulatory cycles. If ovulation has been detected in the current cycle then the algorithm selects the most suitable candidate day to call the First High Point FHP using a system of measurements based on comparisons of each temperature to the phase averages. This is the day on which the temperatures immediately before and after are most consistent with the follicular and luteal phase averages respectively.

On average the FHP temperature is just below the cover line. In a previous study the FHP was 1. An evaluation of the timing of the FHP and the LH peak relative to the data of Ecochard et al is available in Supplementary materials. This means that ovulation itself is estimated to occur on the day of the last low temperature before the rise as suggested by Hilgers and Bailey 46 and Mouzon et al.

Another marker besides the BBT shift that has been used in clinical settings to estimate the day of ovulation is the day of luteal transition DLT defined as the ratio of oestrogen to progesterone falling below a critical threshold. Women using the app who had registered between 1st September and 1st February , had given their consent for the use of their data in research, were aged 18—45 at registration, had a BMI between 15 and 50 and had not been using hormonal contraception within the 12 months prior to registration were included.

Users who stated at registration that they had a PCOS hypothyroidism or endometriosis or who had menopausal symptoms were excluded. They were required to have logged at least ten nondeviating temperatures. Figure 7 summarises the number of users and cycles at each step of the selection process. Users are instructed not to log very light bleeding just before the period as bleeding but to wait until the flow increases. The follicular phase was defined as the first day of recorded menstruation to the EDO.

Luteal phase length was defined as the day after the EDO to the day before the next day of recorded menstruation. We calculated mean cycle length, duration of bleeding bleed length , follicular phase length and luteal phase length in ovulatory cycles.

The following cohort splits by cycle length were defined: very short cycles 15—20 days , short cycles 21—24 days , medium cycles 25—30 days , long cycles 31—35 days and very long cycles 36—50 days.

We calculated the same statistics as well as per-user cycle length variation for cohorts of ovulatory cycles by user age at registration 18—24, 25—29, 30—34, 35—39 and 40—45 years and BMI 15— We also calculated the mean proportion of ovulatory cycles as a fraction of all cycles recorded by the user in each of the age and BMI cohorts.

Owing to the very large sample sizes in this study, P values were not calculated since they can be very small even if differences between cohorts are of no clinical significance. Further information on research design is available in the Nature Research Reporting Summary linked to this article.

The data that support the findings of this study are available from Natural Cycles Nordic AB but restrictions apply to the availability of these data, and so are not publicly available. Data are, however, available from the authors upon reasonable request and with permission of the developers.

The code that constitutes the mobile application including the ovulation detection algorithm is commercially sensitive and not available for release. The code used to analyse the database of recorded cycles may be made available upon reasonable request to the corresponding author and with permission of the company. Wilcox, A. Reed, B. The normal menstrual cycle and the control of ovulation. De Groot, L.

Vollman, R. The menstrual cycle. Major Probl. Google Scholar. Fehring, R. Variability in the phases of the menstrual cycle. Neonatal Nurs. Article Google Scholar. Mihm, M.

The normal menstrual cycle in women. Treloar, A. Variation of the human menstrual cycle through reproductive life. Lenton, E.

Normal variation in the length of the luteal phase of the menstrual cycle: identification of the short luteal phase. BJOG 91 , — Liu, Y. Factors affecting menstrual cycle characteristics. Chiazze, L. The length and variability of the human menstrual cycle. Rowland, A. Effective treatment for luteal phase defect is not clear. That said, you should bring any concerns you have about your menstrual cycle to your doctor.

They might want you to try certain treatments, including:. Your doctor might prescribe progesterone injections or progesterone suppositories if you are undergoing IVF treatment. Progesterone supplementation has been shown to improve the luteal phase and improve pregnancy outcomes with IVF. Get diet and wellness tips to help your kids stay healthy and happy. Progestogen for preventing miscarriage. Cochrane Database Syst Rev. Supplementation with progestogens in the first trimester of pregnancy to prevent miscarriage in women with unexplained recurrent miscarriage: a systematic review and meta-analysis of randomized, controlled trials.

Fertil Steril. Current clinical irrelevance of luteal phase deficiency: a committee opinion. Your Privacy Rights. To change or withdraw your consent choices for VerywellFamily. At any time, you can update your settings through the "EU Privacy" link at the bottom of any page. These choices will be signaled globally to our partners and will not affect browsing data. We and our partners process data to: Actively scan device characteristics for identification. I Accept Show Purposes.

Table of Contents View All. Table of Contents. Overview of Luteal Phase. Luteal Phase Length. Luteal Phase Defect. Miscarriage Risk. Was this page helpful? Thanks for your feedback! Sign Up.

What is the Luteal Phase? When the egg is released, the body enters ovulation , which typically lasts a couple days before the luteal phase begins. Finally, the luteal phase is the second half of your cycle. This is when fertilization and implantation can happen. This part of the menstrual cycle lasts between 10 to 16 days, depending on the woman. At the end of the luteal phase, one of two things will happen: you will either start your period, or you will discover you are pregnant.

Signs of a long luteal phase or pregnancy? Want more info on trying to conceive? While the follicular phase , or first half, of the menstrual cycle can vary in length, in most women, the luteal phase is consistently about 14 days long.

Some women experience a shorter luteal phase, known as luteal phase deficiency LPD , which is the result of decreased progesterone levels that result in inadequate development of the uterine lining. The significance of LPD is controversial. LPD is diagnosed based on a biopsy of the lining of the uterus.

It has been found in women who experience infertility , as well as fertile women, which makes it challenging to interpret the findings of this testing. During the Luteal Phase, the follicle that burst and released the egg during ovulation develops into a small yellow structure, or cyst, called the corpus luteum.