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Everyone’s fertility journey is unique and different. But if you’re going through in-vitro fertilization (IVF), there’s probably one thing that you have in common with everyone else: how much you hate those meds. IVF often entails taking lots of hormonal medications, via pill and through injection. When preparing for embryo transfer (the final step in the IVF process), the medications help your uterus prepare properly for pregnancy and ensure that an embryo has the best chance of implanting. But even the purest, clearest desire for a baby doesn’t quite take the edge off of stabbing yourself with a huge needle every day, or prepare you for the roller-coaster of emotions that those extra hormones can bring.
So what if I told you that there’s a way to do IVF with way fewer of those aggravating medications? No, you didn’t just dream that last sentence. It’s called natural embryo transfer, and for some folks, it’s a fertility game-changer.
What is a natural embryo transfer?
A natural embryo transfer is a type of embryo transfer in which doctors “utilize the patient’s own ovarian follicle development and perform the embryo transfer at the appropriate time in the patient’s natural menstrual cycle,” says Elizabeth Dilday, MD, a board-certified OB/GYN who specializes in reproductive endocrinology and infertility at CCRM Fertility of Newport Beach, CA.
Basically, this method uses the patterns of your existing menstrual cycle to help time when your embryo will be implanted. This type of IVF is also known as natural cycle frozen embryo transfer (FET) or ovulatory FET.
This method is different from medicated frozen embryo transfers because it doesn’t use hormone medications to build up your uterine lining to support a pregnancy. However, the “natural” method isn’t entirely medication-free, Dr. Dilday says. You might still receive a “trigger” injection to spur ovulation, she says, or supplemental hormones after you ovulate to support what your body is already doing.
What does a typical cycle for a natural embryo transfer look like?
To understand how a natural embryo transfer works, it’s important to get a refresher on the ins and outs of the menstrual cycle. Your cycle can be divided into three main events: the follicular phase, ovulation, and the luteal phase.
The follicular phase starts with your period and lasts until ovulation. During this phase (which is typically between days 10 and 21, depending on your cycle), your body starts producing follicle-stimulating hormone (FSH). This hormone prompts your ovaries to get to work growing follicles – small fluid-filled sacs that are found inside the ovaries. While a group of follicles in each menstrual cycle may be able to respond to FSH, only one will ultimately be chosen to release an egg.
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These follicles also produce estrogen, which tells your uterus that it’s time to thicken its lining to prepare for a potential pregnancy. Once estrogen levels peak, your body starts making luteinizing hormone (LH) — which triggers the release of that winning egg during ovulation.
Since a natural cycle FET depends on the patterns of your menstrual cycle, the process of a typical cycle starts when your period does, says Dr. Dilday. “Thereafter, we will monitor for the development of a dominant follicle in the ovary — which has an oocyte inside that is destined for ovulation — and an endometrial lining with appropriate pattern and thickness,” she says. She says that transvaginal ultrasounds, blood tests, and at-home urine ovulation tests (which measure your body’s LH levels) are used to track your cycle and see how your body is preparing for pregnancy.
A day-5 blastocyst-stage embryo is typically transferred five days after ovulation (which is six or seven days after the LH surge), Dr. Dilday says.
As mentioned earlier, your fertility specialist may prescribe medications to help this process along and support implantation. But the prep and practice can vary depending on your clinic and provider, says Dr. Dilday.
What are the potential benefits of a natural embryo transfer?
There are a few potential perks to trying a natural embryo transfer instead of a medicated cycle. For starters, Dr. Dilday says that this form of IVF typically involves taking less medication. (For example, you likely won’t have to do a daily intramuscular progesterone shot at home.) “This may improve patient satisfaction, render the treatment less physically and emotionally taxing, and make the process less costly from a medication standpoint,” she says.
Natural cycle transfers have a similar efficacy rate as programmed cycle transfers, says Dr. Dilday. However, research suggests that the former might offer better maternal and fetal health outcomes. A 2019 study published in the American Journal of Obstetrics and Gynecology found an increased risk of hypertensive disorders during pregnancy with programmed FET compared to natural cycle FET. Another 2019 study from the Journal of Hypertension found that programmed FET cycles were associated with higher rates of preeclampsia compared with modified natural FET cycles (where certain hormonal meds are used to help follicles mature).
What are the downsides of this form of IVF?
Just like any other kind of medical procedure, a natural cycle FET does have a few potential downsides. “This approach has a higher cycle cancellation rate: missing an LH surge may lead to cancellation of an embryo transfer in that cycle,” says Dr. Dilday. Basically, it’s easy to accidentally miss your LH surge or mistime it, which means you have to delay your transfer to the next month.
Scheduling your transfer can also be unreliable, Dr. Dilday adds, because you’re depending on your normal hormonal patterns in your menstrual cycle (and most of our menstrual cycle lengths tend to vary from month to month). As such, “it may not be ideal for patients who may desire more predictability and control, such as those who are accommodating travel or work schedules,” she says. Basically, if you’re not in a position work- or life-wise to drop everything and hustle over to the doctor’s office, this might be a harder method for you to work with.
Taking less medication, as is typical with a natural embryo transfer, also comes with a trade-off. “Natural FET cycles often involve more clinic visits and blood draws compared to programmed FET cycles in order to ‘hone in’ on the correct timing of dominant follicle development, the LH surge, and ovulation, so that the embryo transfer is timed most optimally,” says Dr. Dilday.
It’s also important to note that not everyone is a candidate for natural cycle FET. Basically, it’s ideal if you have regular periods. Unfortunately, some people with fertility issues don’t ovulate regularly thanks to conditions like polycystic ovarian syndrome (PCOS), pituitary gland dysfunction, or who are perimenopausal, says Dr. Dilday. In those cases, you will need additional interventions in the form of medication to help spur the process along.
Dr. Dilday also says that natural cycle FET isn’t always an option at clinics. A 2023 survey of 441 ART clinics in the U.S. showed that 17 percent did not offer natural embryo transfers. There are also sometimes age restrictions on natural cycle FET, Dr. Dilday adds, although that depends on the clinic and the provider.
The bottom line
Natural cycle embryo transfer is a great IVF option for people who have regular periods but are otherwise struggling to conceive, as there are typically fewer medications involved (and thus fewer side effects and costs). It also may be beneficial for maternal and fetal health compared to medicated cycle transfers. But this method does involve more doctor visits and isn’t meant for people who do not ovulate (a huge cause of infertility). Be sure to talk to your trusted fertility specialist to help you figure out what infertility treatments are right for you.
Jessie Van Amburg is a health writer, reporter, and editor with 10 years of experience creating meaningful, compelling journalism in print and digital formats. Her work has been featured in TIME, Women's Health, Well+Good, and more.