Surrogate Medication Requirements: What the Protocol Actually Involves

If you are researching what surrogacy would ask of your body, the medication protocol is the right place to start. Most gestational surrogates take hormones for several weeks before an embryo transfer, and usually into the first trimester. The usual sequence is a drug that suppresses your cycle, then estrogen, then progesterone, often by injection. The exact drugs, doses and timing vary by clinic, and a fertility physician sets them.

This page explains what the protocol generally involves, so you can weigh it before you apply or tell anyone. It is informational. The fertility clinic advises each surrogate on her own protocol, and nothing here replaces that conversation.

Why Medication Is Central to the Surrogacy Process

Gestational surrogacy is different from traditional surrogacy in one way that drives everything else. In traditional surrogacy, the surrogate's own egg is used. In gestational surrogacy, which is what almost all US programmes arrange today, the embryo is created through IVF using the intended parents' or donors' eggs and sperm. You would have no genetic connection to the baby.

Because the embryo is created in a lab, often months earlier and frozen, your body has to be ready on the clinic's schedule rather than your own. In a natural pregnancy, ovulation triggers the hormone changes that thicken the uterine lining and make it receptive. In a gestational cycle, that sequence is replaced with medication, so the lining is prepared on a set timetable and the transfer can be matched to the embryo's stage of development.

The medications are prescribed and monitored by the fertility clinic's reproductive endocrinologist. The surrogacy agency does not prescribe anything. Agencies coordinate, but the medical protocol belongs to the clinic.

No two surrogates receive an identical regimen. The clinic tailors the protocol to your cycle, your health history, how your body has responded in any earlier testing, and the transfer plan for that particular embryo.

The medication phase is one of the most physically demanding parts of the whole process. Wanting to understand it before you apply is a reasonable, practical thing to do.

The Two Phases of a Surrogate Medication Protocol

Think of the pre-transfer protocol as two jobs done in order.

Phase 1: suppression. Your own hormonal cycle is temporarily quieted. This gives the clinic control over timing, so your body does not ovulate or shed its lining at an unplanned moment.

Phase 2: uterine preparation. Estrogen is introduced to build up the uterine lining. Once the lining reaches the thickness the clinic wants, progesterone is added to make it receptive to an embryo.

Both phases happen before the embryo transfer. They are preparation, not pregnancy.

If a pregnancy is confirmed, the medication does not stop there. Estrogen and progesterone typically continue into the first trimester to support the pregnancy until the placenta takes over hormone production, usually somewhere around 10 to 12 weeks.

How long each phase lasts varies by clinic protocol and by how your body responds. Some clinics use a longer suppression phase, some a shorter one, and some adjust mid-cycle based on monitoring results.

Suppression Medications: Controlling the Cycle

The most common suppression drug is a GnRH agonist, usually leuprolide acetate (Lupron). In plain terms, it temporarily quiets the pituitary gland, the part of the brain that signals your ovaries. With those signals paused, the clinic controls the hormonal environment instead of your natural cycle.

Some clinics start with birth control pills for a few weeks before suppression begins. The pills regulate your cycle so the protocol can start on a predictable date.

Leuprolide is usually given as a subcutaneous injection, a small needle just under the skin, often in the abdomen. It is typically self-administered daily. Clinics commonly train surrogates on injection technique before the cycle begins, either in person or through instructional material, and nurses are available for questions.

Common side effects of suppression come from the temporarily low-estrogen state it creates:

• hot flashes
• headaches
• mood changes
• fatigue

These are generally temporary and tend to ease once estrogen is introduced. Throughout this phase, the clinic monitors you through blood draws and ultrasounds. You are not managing it alone.

Estrogen: Building the Uterine Lining

Once suppression is established, estradiol, a form of estrogen, is introduced. Its job is to thicken the uterine lining to a target measurement. Many clinics look for a lining of roughly 8mm or more, but the clinic sets its own threshold and may weigh the lining's appearance as well as its thickness.

Estrogen can be given in several forms:

• oral tablets
• transdermal patches worn on the skin
• vaginal suppositories
• injectable estradiol valerate

The clinic chooses the form, or a combination, based on its protocol and your history. Some clinics change the form partway through if levels are not where they want them.

Monitoring during this phase means ultrasounds to measure the lining and blood draws to check estradiol levels. The clinic adjusts dosing based on the results, which is why these appointments matter.

Common side effects include bloating, breast tenderness, mood changes and headaches.

When the lining reaches the target, the clinic typically confirms the transfer date. That is a milestone, not a guarantee. A transfer can still be postponed if levels shift, if the embryo plan changes, or for other medical reasons.

Progesterone: Preparing for and Supporting Implantation

For most surrogates, this is the hardest part of the protocol physically.

Progesterone turns the estrogen-built lining into an environment where an embryo can implant. It is started a specific number of days before transfer, timed to match the embryo's developmental stage. A day-five embryo, for example, needs the lining to be at the matching point in its cycle.

The most common form is progesterone in oil (PIO), given as an intramuscular (IM) injection. It goes into the upper outer area of the buttock, typically once a day, with a longer needle than the leuprolide injections because it has to reach the muscle.

To be plain about it: IM injections are uncomfortable. Injection sites can become sore, and some surrogates develop small lumps under the skin (nodules). Rotating sides and applying warmth before or after the injection are commonly suggested to help, and the clinic can advise on what it prefers.

Some clinics use vaginal progesterone instead of, or alongside, IM injections. Options include suppositories, inserts such as Endometrin, or gel such as Crinone. The form is the clinic's decision, made on medical grounds. You can ask about alternatives, but you do not choose the form on your own.

Progesterone continues after a positive pregnancy test, typically through the first trimester.

Common side effects include fatigue, bloating, mood changes and injection site soreness.

Because the injection site is hard to reach yourself, a partner, friend or other support person often gives the IM injections. If you live with someone, this is worth discussing with them before you go further, since it means a daily commitment from them as well.

Additional Medications That May Be Part of the Protocol

Beyond the three core hormones, many protocols include supporting medications. None of these is universal.

• Low-dose aspirin. Sometimes used around the time of transfer to support blood flow to the uterus.
• Antibiotics. A short course, such as doxycycline, is often prescribed around transfer to reduce infection risk. In some protocols, the intended parent or parents take a concurrent course.
• Corticosteroids. Methylprednisolone (Medrol) or prednisone is sometimes given briefly around transfer to modulate the immune response.
• Prenatal vitamins. Standard throughout. Clinics typically ask surrogates to start them before the protocol begins.

The specific combination is decided by the reproductive endocrinologist. Before the cycle starts, clinics typically provide a written protocol document listing every medication, its dose, its timing and how it is taken. If anything on it is unclear, that document is the thing to ask about.

FDA Oversight, ASRM Guidelines, and What They Mean for Surrogates

Two different bodies shape how this process runs, and they work in different ways.

The US Food and Drug Administration regulates human cells, tissues, and cellular and tissue-based products under 21 CFR Part 1271. For fertility clinics, this matters most where donated reproductive tissue, such as donor eggs, sperm or embryos, is involved. In plain language, it requires infectious disease screening of donors and documentation of that screening. It is a set of rules about tissue handling and donor eligibility. It does not govern every part of surrogacy, such as contracts, matching or pay. The FDA publishes its tissue regulation material directly, and you can read it there.

The American Society for Reproductive Medicine (ASRM) publishes practice guidance for third-party reproduction, including the evaluation of gestational carriers. These are professional standards, not federal law. Reputable clinics generally follow them, and they shape the common screening criteria you will see discussed: age, BMI, prior pregnancies and psychological evaluation. The common ranges and how they vary are covered in our guide to surrogate qualifications. The medication protocol sits inside that broader medical clearance.

One practical point: your own OB/GYN is typically not the prescribing physician for the IVF protocol. The fertility clinic manages the medications through the transfer and early pregnancy, and care then transitions to your OB.

Medical Screening Before the Protocol Begins

Before any active protocol medication is prescribed, the clinic runs its own medical evaluation. The full sequence is laid out in our explainer on surrogate medical screening. The parts that connect directly to medication are these.

Mock transfer cycle. Many clinics run a mock cycle first, also called a mock embryo transfer or uterine evaluation cycle. You take estrogen and progesterone much as you would in a real cycle, so the clinic can see how your lining responds and confirm your uterine anatomy. Not every clinic requires one.

Infectious disease testing. Clinics commonly test for HIV, hepatitis B and C, syphilis, gonorrhea, chlamydia and CMV. A partner or spouse is typically tested too. Where donor tissue is involved, FDA donor screening rules apply to the donor, and clinics generally build carrier and partner testing into their own screening following professional guidance.

Uterine evaluation. A saline infusion sonogram (SIS) or hysteroscopy checks that the uterine cavity is free of polyps, fibroids or other issues that could affect implantation.

Psychological evaluation. ASRM guidance calls for psychological evaluation of gestational carriers. It is separate from the medication protocol but part of the same clearance sequence.

You would not start the active protocol until the fertility clinic issues medical clearance. Passing an agency's preliminary eligibility review is not the same thing. How these steps fit together, and why they often take months, is covered in the surrogate screening process.

What the Medication Schedule Looks Like Day to Day

During the active protocol, most days involve at least one medication, often more. A typical pre-transfer stretch includes daily injections, patches or suppositories for several weeks. Clinics commonly provide a medication calendar, on paper or through an app, so you can track what to take and when.

Monitoring appointments for blood draws and ultrasounds typically happen every few days during the active protocol. The fertility clinic may not be near where you live. Some clinics arrange local monitoring at a partner facility, while others need you in person. This is worth asking about early, because it affects work, childcare and travel. How travel and related costs are handled is a contract matter; the general structure is explained in base pay vs. allowances.

The embryo transfer itself takes place at the fertility clinic. Depending on distance, that can mean one or two trips.

The protocol is time-sensitive, so clinics expect prompt communication with the coordinator about side effects, questions or a missed dose. If a dose is missed, the instruction is to contact the clinic. Clinics give clear guidance on what happens next, and that decision is theirs.

From the start of suppression to a confirmed pregnancy, the time commitment is typically several weeks to a few months. The exact length depends on the protocol and how your body responds.

After the Transfer: Medications During Early Pregnancy

A pregnancy is confirmed by a beta hCG blood test, usually around 10 to 14 days after transfer. The medications do not stop when the result is positive.

Estrogen and progesterone typically continue through roughly 10 to 12 weeks of pregnancy, until the placenta is producing enough hormones on its own. The fertility clinic monitors you through this early stage with further blood tests and ultrasounds, then transitions your care to your OB/GYN.

Some surrogates are weaned off gradually rather than stopping all at once. The clinic decides the tapering schedule.

If a transfer does not result in pregnancy, the medications are stopped and your cycle returns. The intended parents and the clinic then discuss next steps, which may include another transfer. This is a real possibility, and it helps to think through before you begin how you would feel about another cycle, both emotionally and in terms of time. How agencies handle repeat transfers differs, and it is one of the things worth comparing when you look at what to look for in an agency.

Your Next Step

If you want a clearer read on your own situation, Surrogate Compass offers a free eligibility review with no obligation. The review looks at your age, pregnancy and delivery history, your current medications and health conditions, and the other criteria programmes commonly use, and it shows whether your situation looks likely to meet those common criteria. It is not approval. Agencies and clinics run their own screening, and a physician decides on medical clearance. If you want to see what the application stage involves first, our guide on how to apply to be a surrogate walks through it.

When you are ready, contact Surrogate Compass to request your free eligibility review. There is no deadline, and you can come back whenever it suits you.