Fertility Diet: What To Eat When Trying To Get Pregnant
August 7, 2023 No Comments
Bioidentical progesterone is one of the most powerful tools in my fertility toolkit. If you’re struggling with low progesterone, short luteal phases, recurrent miscarriages, or estrogen dominance, using bioidentical progesterone correctly can make the difference between a positive pregnancy test and another disappointing cycle.
In this guide, I’ll cover exactly how to use bioidentical progesterone for fertility: the difference between cream, oil, and pills; precise timing and dosage; when to start after ovulation; what to do if you get pregnant; and critical precautions that most articles miss.
Table of Contents
Bioidentical progesterone is the identical hormone produced by a woman’s ovary. It’s made from naturally occurring plant steroids found in wild yam (diosgenin), then chemically converted in a lab to match your body’s own progesterone molecule exactly. It is NOT the synthetic version used in oral contraceptives (progestins) or prescriptions like Provera.
Synthetic progestins like Provera can cause severe side effects including increased cancer risk, abnormal menstrual flow, fluid retention, nausea, depression, and elevated risk of heart disease and stroke. Natural bioidentical progesterone, by contrast, has an excellent safety profile—the placenta produces 300+ mg daily during the third trimester, confirming that high levels are safe for a developing baby.
Key benefits of bioidentical progesterone for fertility:
This is one of the most important decisions—and most articles get it wrong.
Studies show that up to 90% of an oral progesterone dose is lost through the liver (first-pass metabolism). You’d need a dose 500% higher than what you actually need to make an impact. Worse, oral processing creates 30+ metabolites in the liver, any of which can cause unwanted side effects. If nature had intended your ovaries to be in your GI tract, oral dosing would make sense—but they’re not.
I always recommend progesterone oil (like BioMatrix Pro-Adapt) or a prescribed vaginal suppository (Endometrin, Prometrium) over a skin cream. Here’s why:
Applying bioidentical progesterone to the mucous epithelial membranes of your vagina provides virtually ideal absorption. These membranes feed directly into the pelvic plexus of veins—the same venous network your ovaries naturally empty into.
From there, progesterone travels unchanged to your heart and is distributed to hormone-sensitive cells throughout your body, exactly as if your ovary produced it.
Before starting bioidentical progesterone, always test first to get a baseline. You have two options:
Optimal luteal phase progesterone: above 15 ng/mL. I like to see at least 15, though many conventional labs consider anything above 10–12 “normal.” If your level is below 15, you’re a strong candidate for bioidentical progesterone support.
I recommend BioMatrix progesterone oil, or ask your doctor to prescribe Endometrin or Prometrium vaginal suppositories.
Step 1: Track ovulation. Use an OPK like the Mira tracker to identify your LH surge.
Step 2: Start progesterone 3 days after your LH surge. This mimics your body’s natural progesterone production timeline. If you don’t detect ovulation by cycle day 18, start progesterone anyway—you’ve likely had an anovulatory cycle and need support.
Step 3: Apply vaginally. Apply progesterone oil or insert suppository at bedtime. Vaginal absorption bypasses the liver and enters the pelvic venous plexus directly.
Step 4: Continue through the luteal phase.
When to start: 3 days after confirmed LH surge. If not ovulating or not cycling, start on cycle day 15.
Standard dose: 40–100 mg/day during the two weeks before expected menses. Apply morning and evening for steady levels.
Important: more is not better. Too much progesterone causes hormonal imbalances just like too little. Start at the lower end and adjust based on symptoms and follow-up testing.
A loading dose is beneficial for women who have had many months (or years) of anovulatory cycles—leading to extreme progesterone depletion. For each cycle without ovulation, estrogen dominance worsens as progesterone stores are depleted.
Loading dose protocol: 40 mg twice daily (morning + evening = 80 mg total) for 1–2 months, starting on cycle day 15 and continuing until menstruation begins. After 2 months, reduce to standard dosage.
Low progesterone while trying to get pregnant can cause recurrent miscarriages. Progesterone maintains the uterine lining, reduces blood clotting risk, and prevents the immune system from rejecting the fetus.
Under the care of a doctor or midwife, bioidentical progesterone can prevent first-trimester miscarriage when low progesterone is the primary cause. By the second trimester, the placenta takes over production. Supplementing with vaginal progesterone also supports successful implantation.
Endometriosis is driven by estrogen dominance. Bioidentical progesterone counterbalances excess estrogen, reduces endometrial tissue growth, and supports the hormonal environment needed for implantation. See: Natural Remedies for Endometriosis.
Women with PCOS often don’t ovulate regularly, leading to chronic progesterone deficiency. Bioidentical progesterone can mimic a natural cycle and help the body re-establish ovulation. See: Natural Remedies for PCOS.
When progesterone drops, estrogen becomes disproportionately high—causing weight gain, heavy periods, breast tenderness, mood swings, and fertility problems. Bioidentical progesterone directly addresses this imbalance. See: Natural Remedies for Estrogen Dominance.
A short luteal phase (less than 10 days between ovulation and menstruation) often indicates insufficient progesterone. The uterine lining doesn’t have enough time to prepare for implantation. Bioidentical progesterone extends and supports the luteal phase, giving a fertilized egg a better chance of implanting successfully.
If you experience any of these, adjust your dose and retest progesterone levels. Work with a practitioner who understands bioidentical hormones.
Estrogen dominance may temporarily worsen. After an extended period of progesterone deficiency, your estrogen receptor sites will be stimulated when you start progesterone. This is actually a good sign—it means your body is responding. You may experience breast tenderness, spotting, fluid retention, or hot flashes for the first 1–2 cycles before levels regulate.
Never stop progesterone cold turkey. Always wean off gradually by slowly reducing the amount over several days. An abrupt drop can trigger bleeding or a miscarriage if you’re pregnant.
Always have a backup supply. Running out mid-cycle causes a sudden progesterone drop that can trigger your period. Keep at least two bottles on hand.
Progesterone can change cycle timing. This is the most common side effect of bioidentical progesterone. Tracking your cycle closely will help you adjust.
Progesterone transforms cervical mucus into “swimming lanes” for sperm after ovulation. If you’re also working on cervical mucus production, see my guide: How to Increase Cervical Fluid to Get Pregnant.
If you’re trying to get pregnant and looking for a solution-based, comprehensive approach, read my complete guide: What’s Actually Preventing Pregnancy — and How to Fix It.
The Fertility Code is the best-kept secret of women who want to take the guesswork out of conceiving, and give themselves every possible chance of getting, and staying, pregnant successfully.
Bringing together a personalized & custom approach, evidence-based information, science-backed protocols, and nurturing practices, this course is for anyone who is struggling to get pregnant, or thinking about getting pregnant soon. The course is a one-stop-shop for getting your body, mind and soul prepared for conception.
In less than 3 months, you will learn exactly what you need to do now to get pregnant successfully and have a healthy full term pregnancy with The Fertility Code.
Sarah Jane Sandy is a certified nutrition therapist, and a fertility and women’s health expert. She has helped hundreds of women increase their fertility naturally and go on to have healthy full-term pregnancies. She has been working with women and couples trying to get pregnant for over 16 years and over 90% of the women who work with her get pregnant and have healthy babies.
She also works with women trying to fix their hormone imbalances, as well as supporting women through pregnancy and the postpartum period. Learn more about her own fertility and hormone journey here. To send Sarah a message, complete her Contact Form.
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