When Does Implantation Occur In Pregnancy?
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Medically reviewed by Renita White, MD
Implantation refers to the process where a fertilized egg attaches itself to the uterine wall. This occurs about 10 days after you ovulate. Once implantation occurs, you are officially pregnant—though pregnancy tests may not detect your pregnancy immediately.
Some people experience symptoms like light bleeding during implantation, but you may not know that your egg has implanted until you get a positive pregnancy test.
Here's everything you need to know about implantation, including how and when it occurs, possible symptoms, how to determine if implantation has occurred, and when to contact a healthcare provider.
When Implantation Happens
To understand when implantation occurs, it’s important to have a clear understanding of the menstrual cycle and where implantation fits in.
Menstrual Cycle
The average menstrual cycle lasts about 28 days, give or take. Menstruation (shedding of your uterine lining) occurs during the first few days of your cycle. This typically lasts about four days, though it varies from person to person.
After your period is over, you enter the follicular phase. The follicular phase is driven by the hormone estrogen. Your ovaries produce small fluid-filled sacs called follicles. Each follicle can potentially release a mature egg for fertilization. The lining of your uterus also begins to thicken to prepare for a possible fertilized egg.
Ovulation occurs around day 14 of your cycle. This phase is driven by two hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH). During ovulation, your ovaries release a mature egg. The egg moves down a fallopian tube, where it usually fertilizes.
After ovulation occurs, you enter the luteal phase of your cycle, which lasts from about day 15-28. During this phase, your body prepares to welcome a fertilized egg and sustain a pregnancy. Progesterone is the key hormone of this phase.
Implantation Date
Implantation occurs during the luteal phase—usually between days 20-24 of your cycle if your cycle lasts 28 days, or about 10 days after you’ve ovulated.
Multiple factors can affect your implantation date, primarily the fact that different people have different menstrual cycle lengths. For example, if your cycle is closer to 21 days, implantation will occur earlier than day 20-24 of your cycle. If your cycle is 35 days, implantation will occur later than day 20-24. Menstrual cycle length depends on things like:
What Happens During Implantation
The journey of your fertilized egg looks like this:
A single-celled zygote is formed when your egg is fertilized by sperm.
The zygote travels through a fallopian tube toward your uterus.
As it travels, the zygote divides and eventually becomes a ball of cells called a blastocyst.
The blastocyst moves to your endometrium (uterine wall) and begins to implant.
Related: Is Having Two Periods in One Month OK?
Symptoms of Implantation
Many people don’t experience any obvious symptoms when implantation takes place. Implantation bleeding is the most common symptom. According to the American College of Obstetricians and Gynecologists (ACOG), implantation bleeding can happen about 1-2 weeks after fertilization.
Up to 25% of people experience implantation bleeding. The bleeding is usually light, similar to spotting, and generally lasts no more than three days. It can be difficult to distinguish between implantation bleeding and premenstrual symptoms because implantation symptoms occur near when you might expect your period.
Here are some general differences between menstrual bleeding and implantation bleeding.
Menstrual Bleeding | Implantation Bleeding |
About 14 days after ovulation | About 9 days after ovulation |
Bright to dark red | Light pink to rust-colored |
Might have clotting | No clotting |
Possibly heavy flow | Light flow or spotting |
4-7 days | 1-2 days |
Other possible implantation symptoms include:
Fatigue: Caused by an increase in the hormone progesterone, as well as the body prioritizing bringing blood and nutrients to the developing fetus
Mild cramping: Less intense than period cramps, may occur in the lower back as well as in the pelvic region
Nausea: Typically beginning 2-8 weeks into the pregnancy
Breast changes: Including soreness and heaviness
Headaches: Caused by hormonal changes
Moodiness: Caused by hormonal changes
Related: Pregnancy Symptoms By Trimester
How to Determine When Implantation Will Happen
Implantation occurs about 10 days after you ovulate and conceive. The best way to determine when implantation occurs is to track your ovulation and learn to recognize its symptoms. Tracking will also maximize the chances that you conceive during a given cycle if that’s your goal.
There are various ways to track your menstrual cycle and pinpoint ovulation, including using a calendar, tracking your basal body temperature, and observing discharge.
The Calendar Method
The calendar method involves recording your menstrual cycle dates for several months to detect patterns. If your cycles are regular, you can estimate when you will ovulate based on your cycle length.
Most people ovulate about two weeks before their periods begin. Here are some average cycle lengths and likely ovulation days:
21-day cycle: Day 7
28-day cycle: Day 14
35-day cycle: Day 21
Basal Body Temperature
Basal body temperature (BBT) is your body's temperature at rest. Your most accurate measure of BBT is your temperature first thing in the morning before you perform any activities.
A menstruating person’s basal body temperature rises slightly after ovulation takes place. If you record your temperature daily using a basal body thermometer and record these daily temperatures on a chart, you should see a pattern of a slight rise in temperature just after ovulation. This method only works if you take your temperature right when you wake up before you get out of bed.
Cervical Mucus Method
You may have noticed that your cervical mucus changes throughout your menstrual cycle. The biggest change usually happens right in the middle of your menstrual cycle, when your mucus becomes more plentiful. Clear and slippery mucus, similar to egg whites, is a sign that you are ovulating or are about to ovulate.
Ovulation Predictor Kits
You can purchase over-the-counter ovulation predictor kits or fertility monitors at most pharmacies. These kits can detect luteinizing hormone (LH), which spikes right before ovulation.
When Should You Take a Pregnancy Test?
No kit or pregnancy test can detect implantation. However, implantation causes a surge in a hormone called human chorionic gonadotropin (hCG). This is what pregnancy tests detect.
Implantation usually occurs about 10 days after you conceive. A pregnancy test may be able to detect pregnancy at that point, but it might take a few extra days. Most pregnancy tests can detect a pregnancy on the day that you’ve missed your period, or even a day or two before. It depends on the test's sensitivity as well as the levels of hCG in your body.
When to Contact a Healthcare Provider
Contact an OB-GYN or certified midwife if you get a positive pregnancy test to discuss the next steps. Prenatal care in early pregnancy is important and will ensure that both you and your baby stay healthy.
Many couples don’t get pregnant right away after trying to conceive. Even after implantation occurs, about one in every three embryos will not survive. Over 50% of pregnancy losses happen before a pregnancy test detects pregnancy. It's normal to try for several cycles without achieving pregnancy.
In some cases, you may want to consult an OB-GYN or reproductive endocrinologist (RE) to discuss your fertility. An RE is a gynecologist who specializes in fertility and infertility. ACOG recommends getting fertility testing if:
You have been trying to conceive for one year and haven’t gotten pregnant
You are over the age of 35 and haven’t conceived after six months of trying
If you are over the age of 40 and are considering pregnancy
Related: A Beginner's Guide to Family Building Using In Vitro Fertilization (IVF)
A Quick Review
Implantation is when your fertilized egg embeds itself in your uterine lining. It signals the beginning of pregnancy. This usually happens about 10 days after you ovulate, or a few days after your expected period. Most people don’t notice implantation, but you might experience symptoms like light bleeding and cramping.
Reach out to your gynecologist or midwife if you have any questions about implantation or getting pregnant. They can guide you and help you decide on an approach that works for you.
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