What Progesterone Does in Early Pregnancy
Progesterone is essential for early and ongoing pregnancy. This powerful hormone lays the foundation for the uterus to accept embryo implantation and for fetal development. Produced first by the corpus luteum and later by the placenta and adrenal glands, progesterone keeps the uterine lining stable after the period so it doesn’t shed and interrupt a pregnancy.
One of progesterone’s main jobs is to suppress uterine contractions so there’s no early pregnancy loss from cramping or embryo displacement. It also modulates the immune response and prevents the uterus from rejecting a fertilized egg. Throughout the menstrual cycle progesterone prepares the endometrium (uterine lining) to accept and support implantation. In the early weeks of pregnancy progesterone is critical to the success of the pregnancy.
Why Progesterone Is Prescribed in Surrogacy
For gestational surrogates progesterone supplementation is almost always required. Since surrogates have medically controlled cycles, rather than ovulating naturally, their bodies don’t always produce enough progesterone to support implantation and pregnancy on their own. Hormone medications regulate the menstrual cycle but external progesterone is needed to mimic the hormonal pattern after ovulation.
Progesterone is especially important in cases of recurrent miscarriage, recurrent abortion or women who have had three or more miscarriages (also known as habitual abortion). These groups have an increased risk of pregnancy loss and are the ideal candidates for progesterone support. Many randomized trials and double blind controlled trials have shown that progesterone improves outcomes in these scenarios by reducing miscarriage rate, lowering the chance of threatened abortion and even improving neonatal factors like birth weight.
For pregnant women undergoing fertility treatments or surrogacy progesterone therapy is a proactive step to improve success rates and sustain a healthy pregnancy.
Types of Progesterone Supplementation Used in Pregnancy
When you or your surrogate begins a fertility journey, progesterone often becomes part of the picture. There are several different ways this hormone can be delivered, and each method has its own strengths depending on your specific medical needs. Your doctor will determine the best approach to give your pregnancy the strongest chance to grow and thrive.
Vaginal Progesterone (Suppositories and Gel)
Vaginal progesterone is often used in IVF and surrogacy to support progesterone implantation. It’s applied as a gel or suppository, delivering the hormone directly to the uterus.
It’s especially helpful for women with vaginal bleeding, threatened miscarriage, or recurrent loss. Studies, including double blind trials and systematic reviews, show it helps reduce uterine contractility, lower preterm labour risk, and may decrease fetal malformations.
Vaginal progesterone is widely trusted and easy to manage, making it a reliable choice during early treatment.
Intramuscular Progesterone Injections (IM)
IM progesterone injections, or “IM shots,” are often used in IVF and surrogacy. They deliver steady hormone levels, especially helpful during the first trimester and sometimes into the third trimester.
These injections are proven effective in randomized trials and are commonly used for women with risk factors like recurrent miscarriage. Though some may experience mild side effects, like skin rash, soreness, or an allergic reaction, they’re usually manageable with guidance.
At Made In The USA Surrogacy, we provide full support and training to ensure surrogates feel confident and cared for throughout the process.
Oral Progesterone (Micronized or Synthetic)
Oral progesterone is a convenient option, often recommended when injections or vaginal forms aren’t ideal. Taken as a pill, it’s easy to add to a daily routine.
Though less directly absorbed, it still supports early pregnancy, especially when paired with other methods. Subgroup analysis and unpublished data suggest benefits for pregnant women over 35 or in the early stages of pregnancy.
Some studies note statistical heterogeneity in results, but many still find it effective. Mild side effects like drowsiness or dizziness are common. For women needing flexible progestogen supplementation, it’s a practical and well-tolerated choice.
OTC and Non-Regulated ‘Progesterone’ Supplements
It can be tempting to browse drugstore shelves or online retailers for progesterone creams or so-called “natural hormone boosters,” especially those containing vitamin C, vitamin B, or plant-based blends. But it’s important to know that over-the-counter progesterone products are not approved for fertility use and are often not safe during pregnancy.
Research published in peer-reviewed journals like Steroid Biochem Mol Biol has shown these products often lack proper dosing, quality control, and consistency. Despite being marketed as gentle or “natural,” they can carry an increased riskbecause they haven’t been tested in systematic reviews or controlled trials.
For that reason, we strongly recommend that only medically prescribed progesterone, from a qualified fertility specialist, be used during IVF, surrogacy, or any pregnancy journey. When the stakes are this high, it’s worth relying on treatments that are backed by science and tailored to your body’s needs.
When Is Progesterone Therapy Prescribed?
After IVF Embryo Transfer
In most IVF and surrogacy cases, progesterone therapy begins 5–6 days before embryo transfer. The hormone helps prepare the uterus for progesterone implantation and supports the embryo during the critical early stages. Supplementation typically continues for at least 10 to 12 weeks of pregnancy, until the placenta fully takes over hormone production.
Ultrasound scans are used to monitor development and confirm implantation. During this time, progesterone helps stabilize the pregnancy and encourages the uterine environment to remain receptive.
For Recurrent Miscarriage and Early Bleeding
Progesterone is commonly used in women with vaginal bleeding, especially those who have experienced three or more miscarriages. This includes women with a history of recurrent abortion or identified risk factors for miscarriage. Clinical guidelines and articles in reproductive biology emphasize that progesterone helps lower the chances of pregnancy loss by supporting endometrial health and embryo viability.
Women receiving treatment for threatened miscarriage benefit significantly from vaginal or IM progesterone, especially when started early and continued through the first trimester.
Preventing Preterm Birth in High-Risk Pregnancies
Vaginal progesterone is also used in women with a short cervix, diagnosed during an ultrasound scan in the second trimester. This protocol helps lower the risk of preterm labour and supports full-term delivery. Studies consistently show this intervention is safe and effective for extending gestation.
While some providers previously used IM formulations like Makena, newer findings show a lack of clinical benefit, and it is no longer recommended in most U.S. fertility centers.
What Do Randomized Controlled Trials Say About Progesterone in Pregnancy?
Data from randomized controlled trials and double blind studies shows strong support for progesterone therapy in improving pregnancy outcomes. A well-conducted systematic review with clearly defined confidence intervals showed that women receiving supplementation had significantly lower rates of miscarriage and preterm birth.
Subgroup analysis indicates especially strong benefits for women with recurrent miscarriage, low progesterone levels, or older maternal age. These studies form the foundation of modern progesterone protocols in surrogacy and fertility care.
Progesterone in the First Trimester: How Long Do Carriers and Intended Moms Take It?
Progesterone therapy usually starts just before embryo transfer and goes through the first trimester, until the 10th or 12th week of pregnancy. This allows the corpus luteum to produce progesterone first and then hand over to the placenta.
Stopping too early can cause low progesterone and compromise embryo development. Clinics use hormone level monitoring and ultrasound scans to guide the discontinuation safely.
Monitoring Progesterone Levels in Early Pregnancy
Progesterone levels are checked through blood tests, especially in the early weeks of pregnancy. Monitoring is crucial in IVF and surrogacy where hormone production is controlled externally. If levels drop, dosage adjustments or delivery method changes are made.
Early detection of progesterone deficiency prevents complications like threatened abortion, vaginal bleeding or miscarriage. Fertility clinics rely on these numbers to make sure every pregnancy gets the hormonal support it needs.
Managing Low Progesterone and Its Symptoms
Women with low progesterone may experience spotting, cramping or changes in discharge. In some cases symptoms go unnoticed until lab work or ultrasound scan shows a potential issue. That’s why proactive hormone monitoring is key.
Providers use data from randomized trials and patient response to adjust progesterone dosages. Prompt treatment reduces the risk of miscarriage and gives a better chance of carrying the pregnancy.
Side Effects of Progesterone Supplementation
Side Effects by Form (Vaginal, Oral, IM)
- Vaginal: May cause discharge, irritation, or skin rash
- IM Injections: Local soreness or mild allergic reaction
- Oral: Drowsiness, nausea, or dizziness
These side effects are generally mild and resolve on their own. The vast majority of surrogates report good tolerance when supported by a clinical team.
Emotional and Physical Support During Hormone Treatment
At Made In The USA Surrogacy, we know the emotional toll hormone treatment can take. That’s why we provide support during every step of your journey. Through regular check-ins, helpful guidance, and a supportive community, we ensure surrogates and intended parents never feel alone.
Our team takes great care to monitor both physical health and emotional well-being throughout clinical practice. You can also refer to this article which breaks down the average cost of IVF in the U.S., explaining what factors affect pricing and how intended parents can plan financially for their fertility journey.
Can You Get Pregnant Without Progesterone Supplementation?
In natural conception, many pregnant women go on to carry full-term pregnancies without hormone therapy. But in assisted reproduction, progesterone is crucial, especially when ovulation is suppressed due to birth control or IVF medications.
In these cases, progesterone helps establish a supportive environment for the embryo during the most fragile early stages of development.
Key Takeaways for Intended Parents and Surrogates
- Progesterone prepares the uterus for healthy pregnancy and embryo implantation
- Supplementation begins pre-transfer and continues through the first trimester
- Forms include vaginal, IM, and oral; only women under medical supervision should use these
- OTC creams with vitamin C or vitamin B are not substitutes for prescription therapy
- Progesterone therapy reduces miscarriage, preterm labour, and improves birth weight
Progesterone Supplements and Pregnancy FAQs
Can progesterone supplements prevent miscarriage?
Yes. A double blind controlled trial and multiple randomised trials have shown that progesterone can reduce miscarriage rate in women with threatened abortion and other risk factors. Medical professionals often prescribe progesterone when early signs like vaginal bleeding or a history of recurrent miscarriage are present. Progesterone helps to stabilise the uterine lining, reduce pain and uterine contractility and improve embryo viability in the early weeks of pregnancy.
How long will I take progesterone?
In most IVF or surrogacy protocols, progesterone therapy starts 5-6 days before embryo transfer and continues through the first trimester. This is usually twelve weeks but some fertility clinics may adjust the schedule based on hormone levels and ongoing ultrasound monitoring. This ensures the uterus is hormonally supported until the placenta takes over natural hormone production.
Is progesterone treatment safe during pregnancy?
Yes. Progesterone supplementation is safe and effective when under medical supervision. It’s FDA approved, has been in clinical practice for decades and has a large body of research including systematic reviews, randomised trials and fertility guidelines. Side effects are usually mild and manageable and the benefits in supporting a viable pregnancy far outweigh the risks in most cases.
What if I miss a dose?
If you miss a dose of progesterone, let your fertility clinic or surrogacy coordinator know as soon as possible. Missing doses can affect the stability of the uterine lining and in some cases increase the risk of complications. Your care team will advise on how to adjust or resume treatment without disrupting the overall protocol. This is why consistent communication and adherence to the schedule is so important during progesterone therapy.
Are natural creams effective?
No. Over the counter or “natural” progesterone creams are not medical grade and often have inconsistent dosages. These products are not backed by relevant articles, peer reviewed research or clinical guidelines. Unlike prescribed progesterone they are not regulated for fertility use and do not support early pregnancy. For best outcomes always use progesterone prescribed by a licensed fertility specialist.
Why is Makena no longer used?
Makena (17-OHPC) was once used to prevent preterm labour in high risk pregnancies. However newer data from randomised trials and a growing body of research failed to confirm its effectiveness. Besides showing minimal clinical benefit there were concerns around side effects and inconsistent outcomes. As a result Makena was taken off the US market and is no longer recommended in clinical practice for preterm birth prevention.
Ready to Start Your Surrogacy Journey?
Whether you’re a hopeful parent ready to grow your family or a compassionate woman considering becoming a surrogate, Made In The USA Surrogacy is here to guide you every step of the way. We partner exclusively with trusted, U.S.-based fertility clinics that are committed to medical excellence and ethical care.
For surrogates, we ensure you receive full progestogen supplementation and medical support from the beginning of your cycle, starting even before your menstrual period is regulated for embryo transfer. Every step of the process is handled with care and professionalism, from hormone therapy through the first trimester and beyond.
We also stay informed by the most up-to-date fertility research, including both published studies and unpublished data, to help shape best practices in care, especially when it comes to treating threatened miscarriage, reducing abortion rate, and ensuring positive outcomes for intended parents and surrogates alike.
If you’re ready to take the next step, explore our Surrogacy Process or contact us today. Every family starts with love, and every journey begins with knowledge, compassion, and a trusted support system.
