In vitro: What is it and how does it work?

In vitro fertilization, known as IVF, is one of the most advanced and effective treatments for infertility. Thanks to medical advances, IVF offers many couples the chance to have children when other treatments have failed. The process is complex and requires precise cooperation between doctors, embryologists and patients.

What does in vitro involve?

In vitro involves the fusion of a woman’s egg cell with a man’s sperm under laboratory conditions. After fertilization, the resulting embryos are cultured for several days, and then one or more embryos are transferred to the woman’s uterus, where they can implant and develop.

Stages of the in vitro process

  1. Stimulation of the ovaries
    • The woman takes hormonal stimulation drugs to stimulate the ovaries to produce more egg cells. Usually this process takes 10 to 14 days.
    • Regular ultrasounds and blood tests monitor the development of ovarian follicles.
  2. Ovarian puncture
    • When the follicles have reached the appropriate size, the doctor performs an ovarian puncture to retrieve mature oocytes. This procedure is performed under ultrasound guidance and under local or general anesthesia.
    • The retrieved ova are then transferred to the embryology laboratory.
  3. Fertilization
    • The collected ova are combined with sperm cells obtained from the man under special laboratory conditions. There are two main methods of fertilization: conventional in vitro fertilization (used quite rarely nowadays) and microinjection of sperm into the egg (ICSI).
    • The choice of method depends on the quality of the sperm and the couple’s previous medical history.
    • A number of additional procedures can also be used in the embryology laboratory to support the fertilization process.
  4. Embryo culture
    • Fertilized ova are cultured in special incubators for 3 to 5 days. During this time, embryologists monitor the development of the embryos.
    • Embryos can be evaluated for quality before transfer. It is also possible to perform genetic testing before administration to rule out hereditary defects and diseases. This is known as preimplantation diagnosis.
  5. Embryo transfer
    • The best-developed embryo (or embryos) is transferred to the woman’s uterus using a thin catheter. Transfer is a quick and usually painless procedure. It takes place without anesthesia.
    • The remaining embryos can be frozen for later use.
  6. Confirmation of pregnancy
    • About 10-14 days after embryo transfer, a woman performs a pregnancy confirmation HCG blood pregnancy test to check for implantation and pregnancy development. More and more experts point out the need for constant monitoring of hormone levels after transfer. A woman should also take regular blood tests beforehand, including estradiol and progesterone and HCG, and discuss the results with her doctor. Based on them, the specialist can administer additional medications to promote the development of pregnancy.

Complications and risks

Like any medical procedure, IVF carries certain risks. The most common complications include:

  • Ovarian hyperstimulation syndrome (OHSS): An overreaction of the ovaries to hormonal stimulation (read more).
  • Multiple pregnancy: Transfer of more than one embryo increases the risk of multiple pregnancies, which can be associated with additional health complications (more information).
  • Risk of infection: Ovarian puncture and embryo transfer procedures carry a minimal risk of infection (more information).

Efficacy of in vitro

The effectiveness of the IVF procedure depends on a number of factors, such as the woman’s age, the cause of infertility, the quality of the embryos and the experience of the medical center. According to studies, the average success rate of one IVF cycle is about 30-40% for women under 35, and decreases with age (more information).


In vitro is a complicated but highly effective treatment for infertility, giving hope to many couples around the world. A thorough understanding of the process, preparation, and collaboration with experienced specialists increase the chances of success and fulfillment of the dream of having a child. With proper preparation and medical support, IVF can become the key to parenthood for many couples.