In Vitro Fertilization (IVF) is a fertility treatment that involves the fertilization of an egg by sperm outside the body. This process takes place in a laboratory setting before the resulting embryo is transferred into the uterus. The journey through an IVF cycle follows a structured timeline, beginning with preparation and concluding with the potential for pregnancy. This article details the sequential steps involved in an IVF cycle.
Getting Started
The IVF journey begins with a preparatory phase, focusing on assessment and planning for both partners. Initial consultations review medical histories and previous fertility treatments. Diagnostic testing includes hormonal evaluations for the female partner to assess ovarian function, and semen analysis for the male partner to evaluate sperm quality. Further female evaluations may include imaging tests like a transvaginal ultrasound or a hysterosalpingogram (HSG) to assess the uterus and fallopian tubes.
Based on these findings, a personalized treatment plan is developed, outlining specific medications, dosages, and procedures. This planning phase can span several weeks to over a month, depending on diagnostic requirements and cycle synchronization needs.
Before active stimulation, pre-cycle medications may be used to synchronize the menstrual cycle or suppress natural hormonal activity. Birth control pills regulate the cycle, allowing better control over ovarian stimulation timing. Gonadotropin-releasing hormone (GnRH) agonists or antagonists may also prevent premature ovulation, ensuring optimal egg collection.
Stimulation and Collection
Following the preparatory phase, controlled ovarian hyperstimulation encourages the ovaries to produce multiple mature eggs. This is achieved through daily injectable medications called gonadotropins, such as FSH or LH, which stimulate ovarian follicle growth. Dosage and duration are carefully monitored and adjusted based on individual response.
This stimulation period, typically 8 to 14 days, involves regular monitoring appointments. These include transvaginal ultrasounds to track follicle growth and blood tests to measure hormone levels, particularly estrogen. This monitoring ensures appropriate ovarian response and helps determine precise timing for egg retrieval.
Once follicles reach optimal size, a “trigger shot” (hCG) induces final egg maturation. This injection precisely times the egg retrieval procedure, occurring 34 to 36 hours later. Egg retrieval is a minor surgical procedure performed under light sedation or general anesthesia, using a transvaginal ultrasound-guided aspiration technique to suction eggs from follicles.
Lab Cultivation
After egg retrieval, collected eggs are transferred to the embryology laboratory. A sperm sample is prepared, either from the male partner or a donor. Fertilization occurs through conventional insemination, where sperm are placed with eggs, or intracytoplasmic sperm injection (ICSI).
ICSI is used for concerns about sperm quality or quantity, or if previous IVF cycles had fertilization issues. With ICSI, a single sperm is injected directly into each mature egg, bypassing fertilization barriers.
Following fertilization, zygotes are placed in specialized culture media and monitored as they develop into embryos. This embryo culture phase typically lasts 3 to 5 days. Embryologists observe development, assessing cell division and morphology.
The goal is for embryos to reach the blastocyst stage, an advanced developmental stage typically occurring on day 5 or 6 of culture. Embryologists assess and grade embryo quality to select the most viable embryo(s) for transfer.
Transfer and Waiting
Once embryos develop, the next step is embryo transfer. This procedure typically occurs 3 or 5 days after egg retrieval, depending on the embryo’s developmental stage. It is generally quick and does not require anesthesia.
A thin, flexible catheter containing the selected embryo(s) is guided through the cervix into the uterus, usually under ultrasound guidance for precise placement. The number of embryos transferred is decided with the medical team, balancing success rates with the risk of multiple pregnancies.
Following transfer, the “two-week wait” period begins, during which progesterone medication is continued. This luteal phase support helps prepare and maintain the uterine lining for embryo implantation. During this waiting period, individuals are advised to avoid strenuous activities and manage expectations.
The emotional experience during this time can be intense, marked by anticipation and uncertainty. At the end of the waiting period, a blood test measures hCG levels to confirm pregnancy. This test provides a definitive result for the IVF cycle’s outcome.