The Luteal Phase: What It Is, How Long It Lasts and What It Does

What is the luteal phase?

The luteal phase is the second half of your menstrual cycle. It starts after ovulation and ends the day before your next period begins. Ovulation divides every cycle into two phases: the follicular phase before it and the luteal phase after it. The luteal phase takes its name from the corpus luteum, the structure the emptied follicle becomes once the egg has been released.

This page is for anyone tracking their cycle, whether you are trying to conceive or trying to make sense of the week before your period. For the whole cycle at a glance, see the phases of the menstrual cycle.

When is the luteal phase, and how long does it last?

It runs from the day after ovulation to the day before your period, roughly the second half of a regular 28-day cycle. The American College of Obstetricians and Gynecologists (ACOG) says that in an average 28-day cycle, ovulation happens about 14 days before the next period starts. The NHS gives a range: the time from the release of an egg to the start of a period "is around 10 to 16 days".

Published studies agree:

The 2019 figures come from Natural Cycles app users: the company funded the study, four authors are its employees or founders, and only cycles with detected ovulation were counted. The authors' 95% interval runs from 7 to 17 days.

Why the luteal phase rarely explains a long or short cycle

ACOG notes that the number of days between ovulation and the start of a period is the most consistent part of the cycle. In the 2019 data, cycles of 21 to 24 days had an average luteal phase of 11.0 days and cycles of 36 to 50 days one of 12.9 days, while the phase before ovulation stretched from 12.4 to 26.8 days. The authors concluded that differences in cycle length were mainly caused by when ovulation happened: see the follicular phase.

What does progesterone do in the luteal phase?

It prepares the womb lining for a pregnancy. The corpus luteum produces progesterone for the rest of the luteal phase, and the NHS describes progesterone's job as helping the womb prepare for a developing embryo to implant. You may notice two other effects:

• Your resting temperature rises. Progesterone has a warming effect. ACOG puts the rise at 0.5 to 1°F (roughly 0.3 to 0.6°C), staying high until the end of the cycle.
• Cervical mucus dries up. ACOG says that just after ovulation the amount of mucus decreases and it becomes thicker and less noticeable.

If no pregnancy starts, the corpus luteum collapses, oestrogen and progesterone fall, and the womb lining is shed as your period. If an embryo implants, it starts making the pregnancy hormone hCG, which the NHS says begins around 6 days after fertilisation. hCG "rescues" the corpus luteum, as reproductive biologists put it, so progesterone keeps coming. That is why early pregnancy and an ordinary luteal phase can feel the same: see two week wait symptoms.

Luteal phase symptoms and mood

Most of what people call luteal phase symptoms are premenstrual symptoms. The NHS lists the most common as mood swings; feeling depressed or irritable; feeling upset, anxious or emotional; tiredness or trouble sleeping; bloating or cramping; breast tenderness; headaches; and changes in appetite or food cravings.

Timing is what makes them premenstrual. ACOG's criteria for premenstrual syndrome (PMS) are symptoms in the 5 days before a period, for at least three cycles in a row, that end within 4 days of the period starting and interfere with some normal activities. Symptoms that last all month point elsewhere: ACOG says depression and anxiety are the conditions that most often overlap with PMS, and about half of women seeking treatment for PMS have one of them.

The NHS suggests regular exercise, a balanced diet, plenty of sleep, yoga or meditation, and a symptom diary over at least 2 cycles to take to a GP. If your period is late and you are unsure which it is, see PMS or pregnancy symptoms.

What if your luteal phase is short?

A luteal phase that is consistently short can be a sign that ovulation is not working as it should. In Lenton's 1984 analysis, every luteal phase of 9 days or fewer was judged abnormal, as were an estimated 74% of 10-day ones. In the 2019 app data, 18% of cycles had a luteal phase under 11 days, and the authors say more research is needed to know whether those are abnormal. The test NICE recommends, and what is sold for it, is covered on short luteal phase.

What does a long luteal phase mean?

Usually one of two things, neither of them a genuinely long luteal phase.

• You may be pregnant. Once hCG has rescued the corpus luteum, progesterone stays up, your temperature stays high and your period does not arrive. The 2019 study flagged possible pregnancies in exactly this way: a luteal phase much longer than the user's average, with temperatures that stayed high.
• Ovulation was dated too early. The 2019 authors note that measuring temperature and LH once every 24 hours limits how precisely phase lengths can be worked out. If an app placed ovulation too early, the phase after it looks long when you actually ovulated late.

If your period has not come more than 16 days after you are confident you ovulated, the top of the NHS range, take a pregnancy test: the NHS says most can be used from the first day of a missed period. If it is negative and you still think you might be pregnant, wait a few days and test again.

To measure your own luteal phase, count from the day after ovulation to the day before your period. Fixing ovulation day is the hard part, because a temperature rise only shows afterwards: how to track ovulation compares the methods, and basal body temperature charting covers charting in detail.

When to get help

• See a GP if premenstrual symptoms are affecting your daily life or lifestyle changes have not helped. The NHS says a GP can advise on treatments.
• Call 999 or go to A&E (your local emergency number outside the UK) if you have symptoms of premenstrual dysphoric disorder (PMDD), a severe form of PMS, and feel suicidal, the NHS says.
• Speak to a GP if a second pregnancy test is negative and your period has still not arrived, as the NHS advises.
• If you are trying to conceive and your luteal phase is consistently short, see when to see a doctor about fertility.

Frequently asked questions

How long is the luteal phase?

Around 10 to 16 days, according to the NHS. A 1984 study that dated ovulation from the LH peak found an average of 14.1 days; a 2019 analysis of 612,613 app-tracked cycles found 12.4 days. It varies less than the first half of the cycle, so a long or short cycle usually reflects when you ovulated.

What discharge is normal in the luteal phase?

Less, and thicker. ACOG says that just after ovulation the amount of cervical mucus decreases and it becomes thicker and less noticeable. The NHS says to see a GP if you are concerned about a change in your vaginal discharge. For the full pattern across a cycle, see understanding cervical mucus.

Why do I feel bloated and emotional in the luteal phase?

Bloating, mood swings and feeling upset, anxious or emotional are among the most common premenstrual symptoms on the NHS list. The NHS says the cause is not fully understood but may be changing hormone levels. ACOG says premenstrual symptoms end within 4 days of your period starting; low mood all month may be depression or anxiety.

Are there foods to eat in the luteal phase?

None of the sources here sets out a luteal-phase diet. For premenstrual symptoms, ACOG in the US suggests complex carbohydrates such as whole grains, beans and lentils, calcium-rich foods, less fat, salt and sugar, avoiding caffeine and alcohol, and smaller, more frequent meals. The NHS advises a healthy, balanced diet.