As the US approaches election day, there’s a national spotlight on a common medical procedure hopeful parents use to grow their families.
After the Alabama Supreme Court ruled (PDF) earlier this year that embryos created through in vitro fertilization have the same legal rights as children, lawmakers and medical providers continue to grapple with the fate of reproductive health procedures that involve embryos and fertilized eggs. Since 2022 when Roe v. Wade was overturned, whether infertility procedures will remain available has become less certain based on state laws.
IVF stands for in vitro fertilization, which is the process of fertilizing an egg with sperm in a medical lab and then implanting the resulting embryo into someone’s uterus, with the hope it will continue to develop into a successful pregnancy and baby.
About 2% of all babies born in the US each year are conceived through IVF, according to the US Centers for Disease Control and Prevention, and use of it has “more than doubled” in the last decade. But despite its growing popularity, IVF remains a complicated procedure, full of financial and sometimes emotional burden for hopeful parents. It also highlights the nuances of human reproduction, whether it be fertilization in a fallopian tube or conception assisted by a little bit of science.
“I think it’s important for people to understand that we, as humans, are not that efficient with reproduction,” Dr. Asima Ahmad, chief medical officer of Carrot Fertility, wrote in an email to CNET earlier this year. Many embryos created in IVF will not make it to a live birth because they won’t continue to grow, or they’ll fail to implant into the uterus and continue as a pregnancy, for example.
Early embryo losses are also common in “natural” conceptions, even before implantation, but unlike in IVF they often go unnoticed and may pass through the body before pregnancy is even detected.
“There are many things that have to align the right way for a live birth to occur,” Ahmad said.
Read more: For These Personal Finance Influencers, Infertility Wasn’t Part of the Plan
People use IVF for many different reasons. These include instances of medical problems that make it difficult for someone to get pregnant naturally, saving childbearing for an age when pregnancy becomes more difficult, and the need for donor eggs or sperm to have a child.
In other cases, people may use IVF or freeze embryos to preserve their fertility if they have a medical procedure that can affect it, like cancer treatment, or if they’re undergoing gender affirmation surgery.
How does IVF work?
Many steps go into IVF treatment — one of the reasons why it’s so expensive — but it’s basically taking a process that has traditionally occurred in the fallopian tube out into the world, with additional reproductive assistance from doctors and embryologists when required by the patient or doctor running the IVF procedure.
Here’s how the process breaks down, according to information from NYU Langone, Johns Hopkins Medicine and Penn Medicine.
Step 1: Collect the eggs
In the month leading up to a natural conception, only one egg is released (sometimes two) during ovulation for potential fertilization and pregnancy. But when conception takes place outside the body, you need more eggs to work with, so you’ll go through an egg retrieval.
Egg retrieval requires whoever is using their eggs for the pregnancy to be given a hormone injection that causes multiple eggs to mature instead of just one. (Many people who are using IVF will use their own eggs to become pregnant, but some patients may find an egg donor or even a surrogate to carry the pregnancy.)
To get the mature eggs from the ovary, you’ll go through a process called follicular aspiration, where a very thin needle is guided through the vagina during an ultrasound. The device will suction out the eggs. You’ll be given medication for this part. (Fun fact: Human egg cells are gigantic compared to the other cells in our body.)
How many times someone will need to go through egg retrieval depends on a few factors, including their reasons for infertility and their age. The number of healthy eggs your body releases declines with age, so an IVF patient in their 40s, for example, may need more eggs and cycles to have a chance at a successful pregnancy. But some people have higher or lower egg quality and quantity due to medical history or individual biology, as is true for sperm, or step No. 2.
Step 2: Collect the sperm
Because much of the sperm-production part of conception takes part outside the body, getting sperm for IVF is less medically involved than retrieving the eggs. Whoever is using their sperm in the pregnancy will probably be asked to abstain from ejaculating for a few days before the collection to ensure a higher sperm count, and most clinics prefer your sample be given in-office.
For those who don’t produce sperm in their ejaculation, contributing to a case of infertility, sperm can sometimes be retrieved in a minor surgical procedure, similar in theory to egg retrieval. Whether you donate sperm before or after the egg donation will be up to your case and your doctor.
Step 3: Lab fertilizes the egg
Once you have eggs and sperm, the next step in IVF (and how the procedure gets its name) is the fertilization of the egg in a lab.
Quickly after the eggs have been retrieved, an embryologist will fertilize the eggs, either by letting a sperm find its own way to the egg, or by injecting a sperm cell directly into the egg (a process called intracytoplasmic sperm injection). Whichever method is used for you will depend on your reasons for IVF or your lab.
Then, everyone waits. It takes about 18 hours to determine whether an egg has been successfully fertilized, and then a couple more days to see if the embryo is developing properly. In many cases, genetic testing of the embryos is done to determine its health or its likelihood of resulting in a baby.
Regardless of fertility status, not every fertilized egg will make it to a healthy embryo. Estimates on how many are lost during a natural conception seem to vary, but as many as one half of fertilized eggs are lost quickly after conception. During IVF, these early losses and failed conceptions are under a microscope, literally.
According to Ahmad, the chance of getting pregnant even in “the most fertile age range” is about 25% to 30% per cycle.
Step 4: Healthy embryo implanted into uterus
Once an embryo is selected and starts to develop, it will be transferred into a uterus for pregnancy to continue normally during a time in the menstrual cycle when the uterine lining can successfully receive it. This is a relatively short procedure where the embryo is released directly into the uterus, passing the cervix.
After some time, patients will know whether the embryo was able to successfully go through the “hatching” process of embed itself into the uterine lining, which then triggers someone’s body to go into pregnancy mode, hopefully resulting in a baby nine months later.
Step 5: Remaining embryos stored if requested
The Alabama court case from earlier this year was centered on embryos that were stored by patients at a fertility clinic.
People often have “extra” embryos if they went through the first parts of the IVF procedure and were able to become pregnant. If someone wants additional children in the future, they may keep those embryos frozen in a protective fluid with the use of liquid nitrogen for whenever they’re ready to try to become pregnant again. The price of embryo storage varies based on the clinic, but may cost at least a few hundred dollars per year, according to an estimate by ReproTech.
Embryos are preserved and frozen using flash-freezing with liquid nitrogen to protect the embryos from forming ice crystals that could damage their cells, according to Johns Hopkins Medicine.
People may be left with stored or additional embryos they don’t know what to do with, have more embryos left than they initially planned for, they’re unable to go through pregnancy again for medical reasons, or they decide not to implant embryos that testing deemed genetically abnormal or those who don’t have a good chance of resulting in a healthy pregnancy.
If embryos are not used or frozen, embryos are discarded as medical waste, or they’re transferred into someone’s womb during a time in the menstrual cycle when pregnancy wouldn’t be possible. They can also be donated to science for research, and even to another person.
Whatever the choice, deciding the fate of remaining embryos created during IVF can be difficult for patients for a variety of reasons. The American Society for Reproductive Medicine, an organization in the field of reproductive science and medical practice, acknowledges the “ethical concerns” unused embryos pose for patients and the clinics that store them. The ASRM calls patient choice a “core value” of reproductive medicine and that patient wishes about their embryos should be “respected if practical and within legal limits.” The legal limits of what you’re able to do as a patient depend on state laws, as well as individual protocols at fertility clinics.
In general, patients have the wheel in deciding how to proceed in their IVF journey, according to Ahmad, which includes whether to only transfer “fresh” embryos and not store any (transferring frozen embryos may be recommended by physicians for different reasons, including a higher chance of pregnancy), and whether or not to do genetic testing. She notes that some fertility clinics may have individual protocols for freezing all embryos for testing or another reason, but choices in IVF should involve a risk-benefit discussion between patients and their doctors.
“Ultimately,” Ahmad said, “the goal is for the best possible outcome for the patient.”
