Natural Cycle FET (Frozen Embryo Transfer)

Learn about the options for preparing your uterus for a FET (Frozen Embryo transfer).

As a women’s health nurse practitioner working in the IVF and surrogacy world since 2007, I have long said, the placenta of an IVF pregnancy is a different breed than the placenta created from a non-IVF pregnancy.  New data supports this observation.  As a result, some IVF clinics are working to do frozen embryo transfers (FET) with a ‘natural’ cycle, rather than the classic protocol of birth control pills + lupon + then stop pills + estrace + then stop Lupron + progesterone = embryo transfer.

If you like what you’ve read here and want Forward Fertility to be part of your surrogacy journey – advocating for you and informed about the details, apply or learn more here:

What are the goals of preparing the uterus for a frozen embryo transfer?

*uterine lining that is greater than 7-9mm in thickness

*uterine lining that has a multilayered or triple layered pattern (see image)

*no fluid in the uterine cavity

*absence of polyps, fibroids, adenomyosis

Historically, a goal that was also included was suppressed ovaries – making sure the pills and lupron you took caused your ovaries to NOT create any follicles.  However, some new studies show that if the medication protocol works with your body, it may result in reducing the risk of pregnancy complications such as hypertensive disease of pregnancy, preterm birth, postpartum hemorrhage and placental issues.  WOW!  That’s awesome, right?

Like many topics in health care, the most common plans or protocols for preparing a woman’s body for a FET (frozen embryo transfer) incorporates the convenience of a predictable schedule, and perhaps at the cost of an optimal outcome (which may come with less convenient consequences).   Let me explain:

With a protocol of: birth control pills + lupon + then stop pills +have baseline ultrasound + estrace  + lining check 1 + lining check 2 + then stop Lupron + progesterone and continued estrace = embryo transfer things are pretty predictable!  95% of the time, at each of the monitoring appointments, the gestational carrier’s lining will be doing exactly what we’d want!

So, why change things?  Two reasons.  First, sometimes this protocol does not work, and it makes sense to try something new.  Second, some data is showing that a different protocol to prepare the uterine lining may have similar pregnancy rates and lower obstetric risks to the gestational carrier (see Pubmed link below for the study).


What are the steps with a Natural Cycle FET?

  1. Monitoring follicular and endometrial development – this may involve several monitoring ultrasounds and bloodwork. The schedule can be unpredictable and is based on how your body is developing the follicles and the uterine lining. Appointments may need to be a possibility any of the 7 days a week, including weekends, possibly.
  2. Monitoring for LH (luteinizing hormone) surge with home ovulation kits.
  3. Documentation of ovulation – with ovulation kits or by taking Ovidrel/hcg to induce ovulation or sometimes both are utilized.
  4. Embryo transfer – date of transfer will vary based on ovulation or date/time of trigger shot – which can be unpredictable
  5. Hormonal supplements are usually given (progesterone and estrogen) after ovulation is confirmed.
  6. Embryo Transfer
  7. Pregnancy test

What are the risks of a Natural Cycle FET?

The downsides of the Natural cycle embryo transfer preparation are that the schedule is not entirely predictable.  You’ll need to have flexible work, childcare, and monitoring facility schedules.  The monitoring can be more expensive, as there typically are more visits with a natural cycle FET than a medicated FET.  Because the woman is ovulating during this cycle, she does need to abstain from any exposure to sperm.  Some IVF clinics suggest a paternity test with a pregnancy to confirm that the pregnancy is indeed NOT the gestational carrier’s and is the child of the Parents-to-be.  It’s possible, even with the monitoring, the IVF clinic could ‘miss’ ovulation and you’d have to restart the process with the next cycle.

What are the benefits of Natural Cycle FET?

The benefits of the Natural Cycle embryo transfer preparation could include: similar pregnancy rates, less medications (particularly Lupron) for the gestational carrier to take, lower costs of medications, and reduced rates of pregnancy induced hypertension conditions and abnormal placental insertion (which improves health outcomes and costs for gestational carrier and parents-to-be).

Not every match will have an IVF clinic who wants to do Natural Cycle FETs.  Also, some gestational carriers do not have work schedules that would allow for them to go to the extra monitoring that may be necessary.  However, a Natural Cycle FET may be just the thing that will help you achieve a pregnancy as a gestational carrier AND could reduce your risk of complications, so asking about it and talking with the Parents-to-be about this possibility is something you may want to bring up.  Ask your agency to help with the discussion if you need some assistance.

Written by: Christie Olsen, APNP – Forward Fertility – 9/2023

If you like what you’ve read here and want Forward Fertility to be part of your surrogacy journey – advocating for you and informed about the details, apply or learn more here: