In Vitro Fertilization (IVF) is a fertility treatment that assists individuals and couples in conceiving. A series of precisely timed hormone injections, administered over several days or weeks, is a fundamental aspect of the IVF process. These injections are precisely timed to optimize the chances of a successful outcome. This article explains when these injections typically begin and how they fit into the broader IVF timeline, noting that individual protocols vary based on a patient’s specific needs.
Before Injections Begin
Before a patient starts IVF injections, several preparatory steps and assessments take place. The process begins with initial consultations where fertility specialists review medical histories for both partners, including prior treatments and health conditions. This evaluation helps identify underlying fertility factors. Fertility assessments, such as blood tests for hormone levels (FSH, AMH) and ultrasounds to assess ovarian reserve and uterine health, are conducted. For male partners, a semen analysis evaluates sperm count and quality.
Following these assessments, the fertility team develops a personalized treatment plan, outlining specific medications and dosages. Clinics conduct baseline assessments, including a transvaginal ultrasound and blood work, usually at the start of a menstrual cycle (around day one or two). This confirms the ovaries are in a resting state and the uterine lining is thin, ensuring readiness for stimulation. Financial counseling and insurance verification are also typically completed during this phase to ensure patients understand the costs involved.
The Injection Journey Timeline
The IVF cycle involves a sequential timeline of injections, each preparing the body for egg retrieval. Ovulation stimulation injections, primarily gonadotropins (FSH and sometimes LH), usually begin on day two or three of the menstrual cycle. These daily injections stimulate the ovaries to produce multiple follicles, each potentially containing an egg, rather than the single egg matured in a natural cycle. This stimulation phase commonly lasts 8 to 14 days, depending on the patient’s ovarian response.
As follicles grow, GnRH antagonists or agonists may be introduced to prevent premature ovulation. These injections stop the body from releasing eggs too early before retrieval. Depending on the IVF protocol, these injections might start from the beginning of the stimulation phase or a few days into it.
The final, precisely timed injection is the “trigger shot,” typically containing human chorionic gonadotropin (hCG). This injection induces the final maturation of the eggs within the follicles, making them ready for retrieval. The trigger shot is given 34 to 36 hours before the scheduled egg retrieval procedure. This timing ensures eggs reach optimal maturity and are collected before natural ovulation.
During the Injection Phase
During the injection phase, patients self-administer many IVF injections. These are typically given subcutaneously (just under the skin) in the abdomen or thigh, with minimal discomfort. Patients receive thorough instruction on proper technique, including mixing and storage, to ensure accuracy and hygiene.
Regular monitoring appointments are a routine part of this phase, requiring clinic visits every one to three days. These visits involve transvaginal ultrasounds to measure follicle size and number, and to assess uterine lining thickness. Blood tests monitor hormone levels (estrogen, progesterone, LH), providing a comprehensive picture of the body’s response to medications.
Based on monitoring results, medication dosages may be adjusted by the fertility specialist. This allows the medical team to optimize follicle growth, prevent overstimulation, and tailor the treatment to the individual’s response.
Next Steps After Injections
After the trigger shot, the egg retrieval procedure is performed approximately 34 to 36 hours later. This minor surgical procedure uses an ultrasound-guided needle to collect mature eggs from the ovarian follicles.
Following retrieval, collected eggs are taken to the laboratory for fertilization, either through conventional insemination or intracytoplasmic sperm injection (ICSI). The fertilized eggs, now embryos, are cultured and monitored for several days as they develop. An embryo transfer may occur a few days after retrieval (fresh transfer) or embryos may be frozen for future use (frozen embryo transfer).
After egg retrieval or embryo transfer, many IVF protocols include luteal phase support, often involving progesterone injections or suppositories. This support helps prepare and maintain the uterine lining, creating an optimal environment for embryo implantation and early pregnancy. This phase continues until a pregnancy test is performed, typically 9 to 14 days after embryo transfer.