Kinderwunsch Düsseldorf / Involuntary childlessness / Fertility basics

Fertility basics

The female fertility cycle



First half of the cycle (usually between days 1-14)

Hormones produced by the pituitary gland stimulate the female sexual organs to produce hormones that cause a follicle (containing an egg cell) to ripen. As the follicle gets larger, the moment of ovulation approaches. At the same time, the follicle produces an increasing amount of oestrogens (E2). These help to thicken and prepare the uterine lining and cause the cervix to open by a few millimeters. They also stimulate the production of cervical mucus, which enables sperm to travel inside the uterus.


Mid-cycle (usually between days 14-16)

The level of oestrogen produced by the follicle peaks and causes the pituitary gland to release luteinising hormone (LH). This stimulates the oocyte (egg cell) to complete maturation, which in turn leads to ovulation. Upon its release, the mature egg is "captured" by one of the fallopian tubes and begins its journey down the tube and towards the uterus.

Approximately 6-7 days after ovulation, 

preparation of the uterine lining has been completed, allowing the embryo to implant in the uterine wall. Hormones produced by the implanted embryo then let the ovaries know that implantation has been successful. The corpus luteum remains intact and produces the hormone progesterone, which is responsible for maintaining the pregnancy.



Second half of the cycle (usually between days 17-18) 

After moving into the fallopian tube, the egg is not fertilised. The absence of human chorionic gonadotrophin (hCG) from the uterus signals to the ovary that fertilisation has not occurred. A corpus luteum is still formed but starts to degenerate and dies after approximately 10 to 14 days. As a result of this, the level of progesterone (which is normally produced by the corpus luteum) in the blood drops. The lining of the uterus starts to disintegrate and is shed. A new menstrual cycle has begun (day 1).


Male fertility


The production of sperm is a physiological process that is governed by hormones and takes place inside the testes. Sperm production starts at puberty. A healthy man will continue to produce sperm for the rest of his life. From start to finish, it takes approximately 12 weeks for sperm cells to develop and mature. The first10 weeks of sperm development take place inside the testes; the sperm then migrate to the epididymis, where they continue to mature. It is during this phase of their maturation process that the sperm gain motility. During sexual intercourse, ejaculation leads to motile sperm being introduced into the vagina. From here, they travel to the cervix and into the uterus, and then all the way to the ovaries. Due to the fact that large numbers of sperm never make it to the site of fertilisation, the body has to produce an excess amount of them.

According to World Health Organisation (WHO) guidelines, a normal semen analysis result is defined as follows:

  • Volume: Ejaculate volume of 2 ml or higher
  • pH-value: 7.2 or higher
  • Sperm concentration: 20 million or higher sperm per ml
  • Total sperm count: 40 million or higher sperm per ejaculate
  • Motility: 50% motile, or 25% with progressive motility within 60 minutes of collection
  • Morphology: 15% or more with normal morphology



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