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The path to parenthood can be a complicated and stressful journey with many avenues for success and failure along the way. If you’ve struggled with infertility or you’re at risk for having a child with an inherited disease, chances are you’re considering in vitro fertilization (IVF) possibly paired with preimplantation genetic testing (PGT) to conceive a healthy baby. However, you might not realize that fertility drugs are a critical component of a successful IVF pregnancy. It’s important to understand the risks involved — including the potential side effects of IVF medication — to make an informed decision before undergoing any medical procedure.

Why Are Fertility Drugs Necessary for IVF?

During a normal 30-day female reproductive cycle, follicles found within the ovaries begin growing that each contains a single immature egg, explains Tyler Treharne, PharmD, owner and founder of independent specialty pharmacy NewEra. “Only one follicle will actually burst and produce a mature egg during ovulation while the others disintegrate,” he continues.

In contrast, IVF involves surgically harvesting multiple eggs before ovulation. Many eggs are needed for the procedure because not all eggs will be successfully fertilized and become viable embryos. Additionally, if you’re pairing IVF with PGT, only embryos that successfully test negative for the specific genetic condition will be transferred to the uterus — therefore, fewer eggs could mean a lower chance of having a successful pregnancy.

To maximize the number of eggs retrievable for IVF, the ovaries are first stimulated using injectable fertility drugs to mature multiple follicles, says Treharne. “For instance, if you have eight follicles, after stimulation they can go in and harvest eggs from all eight of these follicles — now you potentially have eight viable embryos instead of one,” he explains. Additionally, some drugs are used before and during treatment to prevent premature ovulation before the eggs are surgically harvested, he adds.

Common Fertility Medications for IVF

Prior to beginning an IVF treatment, birth control pills are often prescribed to regulate hormone production and allow your initial treatment cycle to be timed more precisely. Once the treatment cycle begins, fertility drugs called gonadotropins are administered to stimulate follicle growth in the ovaries, says Treharne. These injectable medications contain one or both of the naturally occurring hormones — follicle stimulating hormone (FSH) and luteinizing hormone (LH), which both play similar but subtly different roles in reproduction. “FSH and LH both stimulate follicle growth, however a surge of LH at the end fully matures the eggs and helps trigger ovulation,” explains Treharne.

During IVF treatment, a delicate hormonal balance must be maintained to ensure that eggs reach full maturity while preventing ovulation before the eggs are surgically harvested. Gonadotropin-releasing hormone antagonists (GnRH antagonists) and gonadotropin-releasing hormone agonists (GnRH agonists) are injectable medications that work to prevent premature ovulation through interaction with reproductive hormones such as FSH and LH. “A GnRH agonist works by initially flooding the body with FSH and LH, causing a negative feedback loop that shuts off hormone production once the brain detects there’s too much,” explains Treharne. “GnRH antagonists are more commonly used today because they don’t cause that initial surge in hormones,” he continues.

Human chorionic gonadotropin (hCG) is an injectable fertility drug that is a structural analog of LH and a natural hormone. hCG rapidly induces eggs to reach the final stage of maturity. “Timing this shot is critical,” says Treharne. If the eggs haven’t fully matured or are too old they will not be viable for fertilization or development into an embryo, he adds.

Side Effects of Fertility Drugs

While most common side effects of fertility drugs are generally mild and mimic premenstrual symptoms — including nausea, bloating, headache, irritability, restlessness, breast tenderness and hot flashes — some of the more uncommon side effects of IVF medication can be serious.

According to the American Society for Reproductive Medicine, ovarian hyperstimulation syndrome (OHSS) is a mild to severe complication occurring in one percent of patients and caused by the ovaries responding strongly to fertility drugs administered during ovarian stimulation. However, there are multiple checkpoints along the way to mitigate and even prevent OHSS, says Treharne. “The most common side effects we get from these medications are more along the lines of injection site irritations,” elaborates Treharne. “Overall, the risks are minimal.”

According to Treharne, the biggest fear most patients experience is potentially depleting their egg reserves following IVF. “This is simply not the case,” he continues. “If you have eight follicles produced in each cycle, then the fertility medication only serves to allow all eight to produce mature eggs rather than one egg while the rest disintegrate as in a natural cycle.”

Finding Support for Your Journey

To maximize your chances of having a successful pregnancy and an uncomplicated IVF experience, Treharne recommends finding a clinic and pharmacy that will be there with you every step of the way. “You used to walk into your local mom and pop pharmacy where everybody knew you and which medications you were on,” Treharne says. “They were looking out for you and they were your healthcare team.”

Knowing the risks and what your options are, along with having a supportive staff to guide you along your way, empowers you to take control of your health and reproductive decisions. “It’s about the journey and the experience,” concludes Treharne.