The luteal (luteal) phase: what it is, how long it lasts and possible imbalances

Luteal phase

The luteal (or luteal) phase is characterized by the formation of the corpus luteum. It runs between ovulation and the start of the next menstrual period.

Before going into the subject, let’s start with a couple of definitions:

The corpus luteum  is a gland whose function is to produce progesterone.

Counting the days of the menstrual cycle begins on the first day of menstruation, when blood begins to flow from the vagina.

The entire duration of the menstrual cycle can be divided into several phases. The two main ones that take place in the female reproductive system and which make pregnancy possible are,

  • the follicular phase or proliferative phase which has a rather variable temporal length: approximately it goes from the 1st day to the 13th day of the cycle;
  • the luteal phase which is the post-ovulatory phase: approximately it goes from the 15th day to the 28th day of the cycle.

The endometrium is the mucous membrane that lines the uterus internally to prepare for the implantation of a possible fertilized egg cell.

Progesterone  is the main of the progestogen hormones. If an egg is fertilized by a sperm, this hormone stimulates the growth of blood vessels that supply the lining of the uterus (endometrium), but it also stimulates the glands in the endometrium to secrete nutrients that nourish the early embryo.

What is the luteal phase, or luetic phase, or luteal phase

The luteal phase is the post-ovulatory phase of a woman’s fertility cycle. It begins with ovulation and ends with the next menstruation.

Throughout the luteal phase, the endometrium continues to evolve. In the event that the egg is not fertilized, the levels of progesterone (and also estrogen) will drop sharply and, as it is no longer nourished, the endometrium will fall apart with the arrival of menstruation.

What remains (in the ovary) of the follicle that housed the egg released during ovulation is called the corpus luteum, corpus luteum .

The corpus luteum produces progesterone , a hormone that a woman’s body needs to ripen the endometrium (lining of the uterus).
Progesterone turns the endometrium into a nice soft bed in which a fertilized egg can implant, and in which a baby can grow.

Maturation of the uterine lining occurs during each cycle after the egg is released: whether it is fertilized or not.

If the egg is not fertilized, after about 12-16 days the corpus luteum stops producing progesterone.

Luteal phase and fertility

Both the length and quality of her luteal phase can tell a lot about a woman’s fertility.

If this stage is less than 10 days, it may be difficult for you to get pregnant: this is due to the fact that the endometrium is unable to develop sufficiently to accommodate the embryo.

In the lutenic (or luteal) phase there are two types of deficits, one qualitative and one quantitative.

  • Qualitative deficit: the production of progesterone is normal in terms of quantity, but the biological vitality of the corpus luteum is less than 10-11 days.
  • Quantitative deficiency: The corpus luteum lasts for a biologically regular period of time, but its production of progesterone is insufficient.

Fertilization can also take place in both of these cases, but the embryo does not find a suitable environment in which to implant itself.

Therefore, pregnancy cannot occur due to the lack of a place for a fertilized egg to implant and grow.

In fact, there is a difference between fertilization and implantation:

  • Fertilization occurs when the sperm and egg meet, becoming a zygote.This fertilized egg will not become a baby unless it attaches itself to the endometrium and grows there.
  • While you have the implant when the zygote makes “its own house” in the endometrium.

And this is where the pregnancy begins.

If a woman’s luteal phase is characterized by low levels of progesterone (which happens, for example, if her basal body temperature is consistently lower than usual) it may be difficult for her to get pregnant.

Thanks to progesterone, the corpus luteum is able to prepare the uterine mucosa when a fertilized oocyte is implanted.

If there was not an adequate amount of progesterone.

If a woman’s luteal phase is not optimal, she needs to know so she can act accordingly.

Read also: Pregnancy calendar in weeks

The causes of luteal phase deficit

Luteral phase imbalances are usually the result of hormonal imbalances. In order to have a precise diagnosis, in the absence of conception, it is generally used,

  • to an endometrial biopsy: 11-13 days after ovulation;
  • at a dosage of plasma progesterone: on the 21st-22nd day of the ovarian cycle.

In case of a deficit, the therapies foresee the administration of progesterone in the second half of the cycle.

Katherine Johnson, M.D., is a board-certified obstetrician-gynecologist with clinical expertise in general obstetrics and gynecology, family planning, women’s health, and gynecology.

She is affiliated with the Obstetrics and Gynecology division at an undisclosed healthcare institution and the online platform,

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