
updated June 18, 2026
Getting pregnant requires two things to go right: fertilization and implantation. Most women trying to conceive focus heavily on the first — tracking ovulation, timing intercourse, watching for an LH surge. Implantation gets far less attention, even though it’s just as critical.
This matters whether you’ve been told your fertility looks “normal” and you’re still not pregnant, or you have a diagnosis like PCOS, endometriosis, or low progesterone and you’re trying to understand why conception still isn’t happening. In both cases, implantation is often the missing piece of the conversation.
Here’s exactly what implantation is, how to recognize it, and — most importantly — how to actually support it.
Table of Contents
Implantation is the process when the fertilized egg (also called an embryo) attaches to the mother’s uterine wall. The implantation process requires perfect conditions. First, the embryo needs to be healthy, or genetically normal. Second, the uterus needs to be prepared to receive the embryo, meaning it needs to be “sticky” enough for the embryo to be able to implant.
Is it PMS or is it implantation symptoms?
Unfortunately, symptoms of the two are quite similar. Here are some signs and symptoms that implantation may have occurred.
Approximately 10 to 14 days after fertilization, some people experience a small amount of spotting or bleeding.
If cramping does occur, they often happen around the same time as implantation bleeding and feel similar to menstrual cramps. They typically come and go in your lower abdomen or lower back and can feel like a pulling or tugging sensation in your ovarian region.
After implantation, your breasts may become very sensitive to the touch, due to an increase in estrogen, progesterone, and the pregnancy hormone hCG. This usually happens one to two weeks after conception, and it’ll feel more pronounced than normal PMS-related soreness.
Your digestive system slows down when you get pregnant, so some people will experience nausea, constipation, and indigestion (although full-fledged morning sickness is still a few weeks away).
As your body prepares to grow a baby, you may feel more tired than normal. You can partly blame fatigue on the rise of progesterone and increased blood production.
Increased blood volume and surging hormones could cause tension headaches, even if they aren’t something you usually experience.
Rising progesterone levels can cause excess bloating—similar to what you might experience during PMS—which can go hand in hand with constipation.
Just like some people feel extra emotional before their period, they might feel extra moody after implantation due to the rise in pregnancy hormones.
It’s hard to determine through symptoms alone whether implantation has occurred — in fact, the only way to confirm if symptoms are due to implantation or PMS is with a pregnancy test. Please note that it’s also perfectly common for women to experience zero symptoms that implantation has occurred.
Implantation bleeding is light bleeding or spotting that occurs between seven and 14 days after fertilization. It is thought that implantation bleeding only occurs in 10% to 30% of pregnancies.
After ovulation and at the moment an egg is successfully fertilized by sperm in a fallopian tube, the embryo starts dividing and growing. At this time, the inner lining of the uterus, called the endometrium, starts to change. It’s already been thickening throughout the menstrual cycle, but it’ll need to grow and mature even more to protect and nourish an embryo.
Around five to six days after fertilization, the quickly growing embryo moves down the fallopian tube and into the uterus. It’s starting to need more nutrients, and the endometrium has thickened enough at this point to support it.
Next, the embryo attaches itself to the endometrium, where it becomes reliant on the mother’s body — for the first time — for nutrients and oxygen. When the embryo implants, it can disrupt tiny blood vessels in the spot it burrows into …
Which is what causes implantation bleeding.
How do we know if it’s implantation bleeding or your normal menstrual flow?
Implantation bleeding is usually a small amount of light spotting, it doesn’t progressively get heavier like a period, and it usually lasts for only a day or two. It’s never enough to fill a pad or tampon like a menstrual period, nor is it a mix of blood and tissue like a period.
The color is also different than your normal period blood—implantation bleeding is a much lighter hue, typically a very light pink or light rust color.
Light bleeding or spotting, mild cramping, a woozy feeling, swollen breasts and headaches are some commonly reported symptoms associated with implantation bleeding.
The “stickiness” of your uterine lining — i.e. how receptive it will be to an embryo — depends, among other things, on two very important hormones: estrogen and progesterone.
During the first half of your cycle, leading up to ovulation, your ovaries produce estrogen, whose job it is to make your uterine lining nice and thick, in preparation for a fertilized egg to securely implant.
Around mid-cyle, the brain releases the hormone LH (luteinizing hormone) which triggers the dominant follicle to release an egg from the ovary. How do you know if you’re ovulating? Here are some of the most common signs, but there can be additional signs and symptoms around ovulation that are unique to you and your cycle:
increased libido and sexual desire
Mittelschmerz pain [one-sided lower abdominal pain]
After ovulation occurs, the corpus luteum (the empty follicle sac leftover after the egg is released) begins to produce the hormone progesterone that makes your uterus a healthy environment for a developing fetus. A new corpus luteum forms each time you ovulate and breaks down once you no longer need it to make progesterone. Without the corpus luteum, your uterus wouldn’t be able to make the changes needed for a fertilized egg to become a fetus. This increase of progesterone makes your already thickened uterine lining super sticky.
Progesterone is also what stabilizes the uterine lining so the embryo can successfully implant, staying nice and cozy and secure in mama’s uterine lining. Without enough progesterone, it can be more difficult for an embryo to successfully implant. If implantation is successful, the thickened lining is the source of nourishment for the implanted embryo during the next few weeks until the placenta develops and takes over.
To assess whether you are actually ovulating (confirmed by elevated progesterone levels 1 week after a LH surge), and whether your progesterone levels are staying elevated for long enough for implantation to occur successfully, I recommend testing Pdg levels (a progesterone metabolite) using at-home urine tests such as Mira Fertility or Proov to confirm that levels remain elevated for long enough to allow for the best possible chance of successful implantation.
When testing, you want to see PdG levels staying elevated on days 7, 8, 9, and 10 after your peak fertility day (the day you get a positive LH surge). I also suggest requesting a blood progesterone level from your doctor 6-8 days after your confirmed LH surge. We want to see serum progesterone levels ideally above 12 (I like to see them above 15) to support successful implantation.
Sufficient progesterone levels during the implantation window are crucial for the health of an early pregnancy, so this time is nearly as important as ovulation! In fact, studies show that up to 75% of pregnancy losses occur due to failed implantation. Additionally, low PdG (a metabolite of progesterone) is associated with a higher rate of early miscarriage.
Many women assume their bodies will produce enough progesterone to allow for implantation of an embryo. However, when a woman does not produce enough progesterone for long enough during the luteal phase, it makes it more difficult for an embryo to successfully implant and thrive in the uterine wall.
Low progesterone can cause a variety of symptoms, some obvious and some subtle. Many of the symptoms of low progesterone coincide with symptoms of other health issues, so be aware that just because you may have some of these, it doesn’t always mean your progesterone levels are low, but of course it’s worth looking into.
Irregular cycles could mean that your cycles are longer or shorter than normal, come sporadically, or you don’t have a period at all.
Short cycles, usually known as Luteal Phase Defect; cycles are usually less than 25 days.
Anovulatory cycles means you are not ovulating and without ovulation, your body doesn’t produce progesterone.
Menstrual issues like Polycystic Ovary Syndrome (PCOS), Endometriosis, mid-cycle spotting, severe menstrual cramps and PMS symptoms like swollen breasts and water retention.
Infertility, difficulty conceiving, recurrent early miscarriage(s), not ovulating.
Low libido, “foggy” brain, memory lapses, chronic fatigue.
Emotional issues like depression, anxiety, mood swings, heart palpitations, and sleep disturbances.
Skin issues like acne, facial hair, brittle nails, cracked and dry skin.
Weight gain, low thyroid, water retention, and obesity.
Other medical issues like allergy symptoms, migraines, joint pains, hot flashes, night sweats, incontinence, and bone loss.
If you’ve been told your fertility workup looks normal but you’re still not getting pregnant — or you keep getting pregnant and then losing the pregnancy early — progesterone and implantation function are two of the most commonly under-investigated pieces of the puzzle.
Standard testing often checks a single progesterone level on a single day. But what actually matters for implantation is whether progesterone stays elevated for long enough across the entire luteal phase — which a single blood draw can easily miss.
This is true whether you’ve been labeled with unexplained infertility, or you have a diagnosis like PCOS or endometriosis that can independently affect progesterone production and implantation receptivity. In both cases, the fix is the same: test thoroughly, not just once, and look at the full picture rather than a single data point.
This is exactly the kind of hidden driver that gets missed when fertility challenges get labeled “unexplained.” It’s rarely unexplained. It’s uninvestigated.
If you’re still in the early stages of figuring out what’s preventing pregnancy, start here: What’s Actually Preventing Pregnancy — and How to Fix It.
One of the best ways to improve your chances of implantation is by supporting robust progesterone production. This is done through diet changes, lifestyle modifications, and targeted supplementation. You can read more about how to increase progesterone and boost your fertility here.
This includes healthy fat sources as cholesterol is used to produce steroid hormones like progesterone. Choose healthy fats like grass fed butter/ghee, coconut oil, olive oil, raw nuts & seeds, egg yolks and wild caught seafood, and grass fed beef.
Foods rich in vitamin B6, zinc, and magnesium are also important for healthy progesterone levels: grass-fed liver and other organ meats, wild caught salmon, oysters, organic chicken, egg yolks, beans, leafy greens, nuts and seeds, bananas, organic dark chocolate, and avocado.
Seed cycling is the practice of eating specific seeds during the two main phases of your menstrual cycle—follicular and luteal—to help promote the healthy balance of estrogen and progesterone levels.
During the follicular phase, the phytoestrogens in flax seeds can help increase or decrease estrogen levels as needed. Zinc from pumpkin seeds supports estrogen and promotes progesterone production in preparation for the next phase of the cycle.
During the luteal phase, lignans—a type of polyphenol—in sesame seeds inhibit estrogen levels from increasing too much. The vitamin E in sunflower seeds helps boost progesterone levels.
On cycle day 1 until ovulation: eat 1 tbsp of freshly ground flaxseeds and 1 tbsp pumpkin seeds. From ovulation on, eat 1 tbsp sesame seeds and 1 tbsp sunflower seeds.
Make sure to use fresh, whole seeds that you grind yourself, no pre-ground seeds! You can add them to salads, or eat by the handful.
The most important nutrients for optimal progesterone production include:
Magnesium regulates the pituitary gland, which regulates hormone levels. The pituitary gland regulates the production of FSH (follicular stimulating) and LH (luteinizing) that in turn regulate the production of estrogen and progesterone. When it is lacking, your body will produce less of the necessary hormones that keep your reproductive system in good shape.
Vitamin B6 helps to regulate your hormones. One research study has shown that taking Vitamin B6 at doses of 200-800 mg/day can reduce blood estrogen levels, increase progesterone levels and result in improvements in PMS symptoms. Research published in the American Journal of Epidemiology found that poor vitamin B6 status was associated with a lower probability of conception and a higher risk of early pregnancy loss.
Maca style works by controlling estrogen and progesterone in the body. Estrogen or progesterone levels that are high or low at the wrong time can keep a woman from becoming pregnant or keep her from carrying a pregnancy to term. Excess estrogen levels also cause progesterone levels to decline, known as estrogen dominance.
DIM (diindolylmethane), is a compound that helps to support healthy estrogen metabolism. DIM balances the hormones by helping the liver to break down estrogen and remove it from the body. As we already know, too much estrogen leads to lowered progesterone production. By cleansing the body of excess estrogens, DIM can help your body balance its progesterone levels.
Vitex is one of the most powerful herbs for women’s fertility and menstrual health. One of the reasons Vitex is so effective and popular is because of its ability to balance hormones while not containing hormones itself. Vitex increases progesterone by increasing luteinizing hormone (LH) and inhibiting follicle-stimulating hormone (FSH) Vitex supports hormonal balance in the body by having an effect on the hypothalamic-pituitary-ovarian axis (hormonal feedback loop), correcting the problem at the source.
Stress is probably the biggest cause of low progesterone.When your body is stressed, it works to produce higher levels of the hormone cortisol which manages stress in your body. Because progesterone is the precursor to cortisol, when cortisol levels increase, progesterone levels decrease. Stress can be due to any number of things in our modern day: nutritional stress (not eating enough/not eating enough nutrients), emotional stress, or physical stress. Regardless, we have to address the underlying causes of stress and implement changes that can help naturally decrease the negative effects of stress on our body and our hormones. The present world is filled with stress, that’s non-negotiable. But how you respond and react to stress is entirely in your control. Practice managing your daily stressors with ease
If your progesterone levels are lower than optimal in the luteal phase (less than 15 ng/mL) – ask your doctor to prescribe either Endometrin or Prometrium bioidentical vaginal suppository progesterone. You will start using the progesterone 3 days after you’re confirmed an LH surge. Supplementing with vaginal progesterone has been shown to support successful implantation and maintenance of pregnancy.
I also like the ProgestAvail bioidenticial progesterone oil that can be purchased over the counter and is highly effective. To read more about dosing and how bioidentical progesterone works, see Using Bioidentical Progesterone to Naturally increase Progesterone Levels.
I always suggest requesting a blood progesterone level from your doctor 6-8 days after your confirmed LH surge. We want to see serum progesterone levels ideally above 12 (I like to see them above 15) to support successful implantation.
Implantation is the process when the fertilized egg attaches to the mother’s uterine wall. When the blastocyst burrows into the uterine lining successfully—this is called implantation. The implantation process requires perfect conditions. First, the embryo needs to be healthy, or genetically normal. Second, the uterus needs to be prepared to receive the embryo, meaning it needs to be “sticky” enough for the embryo to be able to implant.
Unfortunately, PMS symptoms and implantation symptoms can be quite similar. Some symptoms of implantation are: implantation bleeding, implantation cramps, tender breasts, nausea, fatigue, headaches, bloating, and mood swings.
Here are some of the most common signs, but there can be additional signs and symptoms around ovulation that are unique to you and your cycle: presence of raw egg white consistency cervical fluid, a lubricative sensation on wiping, increased basal body temperature, increased libido and sexual desire, Mittelschmerz pain, and a change in cervix position.
Implantation bleeding is usually a small amount of light spotting, it doesn’t progressively get heavier like a period, and it usually lasts for only a day or two. It’s never enough to fill a pad or tampon like a menstrual period, nor is it a mix of blood and tissue like a period.
The color is also different than your normal period blood—implantation bleeding is a much lighter hue, typically a very light pink or light rust color.
Light bleeding or spotting, mild cramping, a woozy feeling, swollen breasts and headaches are some commonly reported symptoms associated with implantation bleeding.
Low progesterone can cause a variety of symptoms, some obvious and some subtle. Symptoms of low progesterone can include: irregular / short cycles, PMS symptoms like swollen breasts and water retention before your period, infertility, recurrent miscarriage, loss of energy and sex drive, anxiety, sleep issues, and weight gain.
Symptoms genuinely overlap — both can involve cramping, tender breasts, fatigue, and mood changes. The only reliable way to know is a pregnancy test, ideally taken after a missed period for the most accurate result. Tracking your cycle and testing progesterone metabolites can also help clarify what’s happening before a missed period.
Yes. If progesterone isn’t sustained long enough during the luteal phase, an embryo can implant initially but fail to continue developing, which can result in what looks like a regular period arriving on time or slightly late. This is sometimes called a “chemical pregnancy” and often goes unnoticed.
Both. PCOS is most commonly discussed in relation to ovulation, but it can also affect uterine lining quality and progesterone production, both of which matter for implantation. Addressing PCOS for fertility purposes often needs to include implantation support, not just ovulation support.
In many cases, very little. “Unexplained infertility” is a label given when standard testing doesn’t identify a clear cause — but standard testing frequently doesn’t dig deeply into luteal phase progesterone patterns or implantation markers. A more thorough investigation often reveals a specific, addressable factor.
Testing first is always the better approach. Progesterone needs vary significantly between individuals, and supplementing without knowing your actual levels and pattern can mean either under-supporting or over-supplementing. A personalized protocol based on your specific labs is more effective and safer.
Whether you’ve been told everything looks normal, or you’re managing a diagnosis like PCOS, endometriosis, or low progesterone, implantation is one of the most overlooked pieces of the fertility puzzle — and one of the most addressable once it’s properly investigated.
The Fertility Code is my 12-week, high-touch fertility program designed to identify the hidden drivers preventing pregnancy — including progesterone and implantation issues that standard testing often misses — and build a strategic personalized plan so you can get pregnant, naturally or through IVF, without losing another month to confusion or failed cycles.
More than 90% of the women who complete The Fertility Code go on to conceive.



© 2026 Sarah Jane Sandy. All rights reserved. Privacy Policy | Terms and Conditions | Medical Disclaimer | Editorial Policy

Curious about your fertility health? Take this simple quiz to find out what factors may be harming your fertility, and learn what you can do about it!