Implantation: Timing of Early Pregnancy Symptoms

Medically reviewed by Peter Weiss, MD

Implantation is when a fertilized egg attaches to the uterine lining in early pregnancy. This typically occurs six to 12 days after having unprotected sex. The process is not intense or painful, so you may not notice when implantation happens. But some subtle symptoms can occur.

This article reviews common implantation symptoms, what makes implantation different from PMS, other conditions that can mimic implantation and possible early pregnancy complications.

Common Implantation Symptoms

Implantation is usually a silent and painless process that occurs six to 12 days after conception. Most people do not feel it happening. However, some report experiencing the following mild symptoms:

• Implantation bleeding: A small amount of pink or a light rusty brown vaginal discharge, this spotting is not heavy enough to fill a pad or tampon.

• Mild cramping: A light pulling or spasm in the abdomen (belly) or pelvis (between the hips), implantation cramps are usually less intense and not as persistent as period cramps.

• Breast discomfort: This includes breast tenderness and fullness.

• Mood swings: Heightened emotions or crying more than usual may occur.

• Fatigue: Feeling overly tired is a classic sign.

• Change in body temperature: Basal body temperature increases slightly during ovulation and can be high until your period. If it remains elevated a couple of weeks after ovulation, especially if you don’t start your period, this may indicate pregnancy.

Related: Implantation Bleeding vs. Periods

Timing Starting From Ovulation

Several stages, beginning with ovulation, lead to implantation as follows.

• Ovulation: The ovary releases an egg about 14 days before your period.

• Fertilization: If you have unprotected sex around ovulation, sperm travels to penetrate the egg in the fallopian tubes. This union marks fertilization and conception. It can take 30 minutes or up to 24 hours.

• Trip to the uterus: The fertilized egg (zygote) travels to the uterus around six to seven days after fertilization. During its journey, the zygote splits into cells, forming a blastocyst.

• Finding a spot: The blastocyst floats around in the uterus for a bit, looking for a good place to stick into the uterus wall.

• Implantation: About six to nine days after fertilization, the blastocyst fully attaches to the uterine lining to get closer to the blood supply. The uterine wall wraps around the blastocyst and makes it comfortable.

• Forming parts: The outer part of the blastocyst becomes the placenta, and the inner part turns into the embryo.

Related: How Long Does It Take to Get Pregnant?

What Makes Implantation Different From PMS Symptoms?

Premenstrual syndrome (PMS) are symptoms that can occur in a week or two leading up to your period. Implantation symptoms are subtle and occur around the same time, making it easy to mistake them for PMS. PMS symptoms include:

• Abdominal (belly) cramping

• Mood swings

• Bloating

• Breast tenderness

PMS belly cramps are stronger and more persistent than implantation cramps. They resolve within a few days of starting your period. Implantation cramps are typically milder and less persistent spasms or twinges. These cramps can occur throughout the first trimester.

Some people mistake implantation bleeding for their period. But with implantation bleeding, the flow and color are lighter, and it rarely produces blood clots. It lasts only one to two days rather than three to seven days, like a period.

Do You Test Positive for Pregnancy Before Implantation?

A home pregnancy test will not indicate a positive before implantation. Pregnancy tests work by detecting human chorionic gonadotropin (HCG), a hormone that the developing placenta produces.

It takes HCG levels a few days after implantation to reach a detectable level. Most tests can detect pregnancy on or after a missed period, about two weeks after fertilization.

Less Common Implantation Symptoms

While the following symptoms may not occur until a few weeks into pregnancy, the hormone shifts can cause them with implantation:

• Breast or nipple changes

• Appetite changes

• Fullness in the pelvic (between the hips) region

• Heightened sense of smell

• Hypersalivation (feeling like you need to spit a lot)

• Increased libido (sexual desire)

• Lightheadedness

• Metallic taste

• Nausea

Events and Conditions That Mimic Implantation Symptoms

Implantation symptoms are not exclusive to pregnancy. The following conditions and events can mimic implantation symptoms.

• Bladder conditions: Urinary tract infections (UTIs) or interstitial cystitis (IC) can cause abdominal or pelvic pressure.

• Cancer: Endometrial and cervical cancer can cause breakthrough bleeding, cramping, fatigue, and nausea.

• Endometriosis: Endometriosis is when endometrial-like tissue (lesion) grows outside the uterus. It can cause spotting and cramping.

• Gastrointestinal disorders: Irritable bowel syndrome (IBS) or gastrointestinal infections can cause abdominal cramps and bloating.

• Hormonal medications: Hormonal contraceptives or fertility medications can lead to mood swings or breakthrough bleeding.

• Illness or infection: Illness or infections can lead to fatigue, nausea, and elevated body temperature.

• Lifestyle factors: Stress, extreme dieting, excessive exercising, or significant weight change can cause breakthrough bleeding, fatigue, and nausea.

• Medical conditions: Polycystic ovary syndrome (PCOS), pituitary adenomas, and thyroid conditions can cause hormonal imbalances. This can cause menstrual cycle changes, dizziness, and fatigue.

• Ovulation: Ovulation can cause mild cramping, spotting, increased vaginal discharge, mood swings, breast tenderness, bloating, and increased libido. While ovulation occurs in the middle of your menstrual cycle, and implantation occurs 10–14 days after ovulation, timing can be confusing if you have irregular periods.

• Perimenopause: Perimenopause causes hormone shifts that can lead to breakthrough bleeding, moodiness, and fatigue.

• Pseudocyesis: Mental health condition where a non-pregnant person develops pregnancy symptoms.

• Sexual activity: Sexual activity can cause increased vaginal discharge and nipple sensitivity.

• Sexually transmitted infections (STIs): STIs can cause pelvic pain, urinary (pee) urgency, abdominal cramping, changes in vaginal discharge, nausea, and vaginal bleeding. 
  

Complications

Complications can arise during early pregnancy. Two concerns are miscarriage and ectopic pregnancy.

Miscarriage is the loss of a pregnancy before 20 weeks. It can occur due to chromosomal abnormalities, hormonal issues, implantation failure, or problems with the uterus or cervix. Symptoms may include:

• Vaginal bleeding

• Abdominal cramping

• Passing tissue or clots from the vagina

• Stomach upset

• Weakness

An ectopic pregnancy is when the fertilized egg implants outside the uterus. This can lead to severe complications, including rupture of the fallopian tube and internal bleeding. Ectopic pregnancies require immediate medical attention. Symptoms may include:

• Pelvic pain

• Vaginal bleeding

• Shoulder pain

• Dizziness

• Rectal pressure

• Low blood pressure

While symptoms of a miscarriage or ectopic pregnancy can be scary, please note that they do not necessarily mean a complication is occurring. However, if you are pregnant or trying to conceive and experience severe pain or heavy bleeding, it’s critical to seek prompt medical attention.

Summary

Implantation symptoms are subtle signs some people experience when a fertilized egg attaches to the uterine lining in early pregnancy. These symptoms occur around six to 12 days after conception.

Symptoms may include light spotting, mild cramping, elevated body temperature, increased vaginal discharge, and breast changes. Because symptoms can overlap with other conditions, they are not definitive indicators of pregnancy. The most reliable way to confirm pregnancy is through a pregnancy test and consultation with a healthcare provider.

Read the original article on Verywell Health.