Spotting in early pregnancy is common and usually harmless. Up to 25% of pregnant people experience some bleeding in the first trimester, and in most cases, the pregnancy continues normally. The causes range from the routine (a fertilized egg attaching to the uterine wall) to the rare but serious (an ectopic pregnancy). Understanding the differences can help you recognize what’s happening in your body and when to seek care.
Implantation Bleeding
The most common cause of very early spotting is implantation bleeding. When a fertilized egg burrows into the lining of your uterus, it can disturb tiny blood vessels and produce light bleeding. This typically happens 10 to 14 days after ovulation, which means it often shows up right around the time you’d expect your period. That timing confuses a lot of people into thinking it’s just a light or unusual period.
Implantation bleeding looks different from a period. The blood is usually pink or brown rather than bright red, and the flow is much lighter, more like occasional spotting than a steady bleed. It lasts anywhere from a few hours to about two days and stops on its own without any treatment. You won’t need a pad for it. If the bleeding is heavy enough to fill a pad or lasts longer than a couple of days, something else is likely going on.
Cervical Changes From Pregnancy Hormones
Pregnancy floods your body with estrogen, and one of its effects is changing the surface of your cervix. Rising estrogen can cause a condition called cervical ectropion, where the softer, more delicate cells that normally line the inside of the cervical canal become exposed on the outer surface. These cells are fragile and bleed easily when touched.
This is why many people notice spotting after sex, a pelvic exam, or a transvaginal ultrasound during pregnancy. The cervix also develops a much richer blood supply in early pregnancy, making those already-delicate blood vessels even more prone to minor bleeding. This type of spotting is typically light, pink or brownish, and resolves quickly. It’s not a sign that sex or exams are harming the pregnancy.
Low Progesterone
Progesterone is the hormone responsible for maintaining your uterine lining in the early weeks of pregnancy, before the placenta takes over. When progesterone levels are too low, the lining can become unstable and shed small amounts of blood, causing spotting. Other signs of low progesterone can include cramping and, in some cases, recurrent pregnancy loss.
If your provider suspects low progesterone, a blood test can confirm it. Supplementation is available as vaginal suppositories, oral pills, or injections, and it’s commonly prescribed for people undergoing fertility treatments or those with a history of early losses. The supplements are generally considered low-risk, though the evidence on whether they prevent miscarriage in all situations is still evolving.
Subchorionic Hematoma
A subchorionic hematoma is a pocket of blood that collects between the uterine wall and the membranes surrounding the embryo. It’s one of the more common findings on early ultrasounds, and it can cause anything from light spotting to heavier, more alarming bleeding. The blood is often dark brown or red.
Research published in Frontiers in Medicine found that pregnancies with a subchorionic hematoma had a miscarriage rate of about 13.5%, compared to 8.3% in pregnancies without one. That means the vast majority of these pregnancies, roughly 86.5%, still resulted in a live birth. The risk of complications increased with the size of the hematoma relative to the gestational sac, so your provider will likely monitor it with repeat ultrasounds. Most small hematomas resolve on their own as the pregnancy progresses.
Infections
Vaginal or cervical infections can irritate tissue and cause spotting during pregnancy. Bacterial vaginosis, yeast infections, and sexually transmitted infections like chlamydia or gonorrhea can all produce light bleeding, sometimes accompanied by unusual discharge, odor, or irritation. If your spotting comes with discharge that looks or smells different from normal, an infection is worth investigating. These are typically straightforward to treat during pregnancy, and treating them promptly reduces the risk of complications.
Miscarriage
Spotting can be an early sign of miscarriage, though bleeding alone doesn’t mean a pregnancy is ending. The key differences lie in the volume, pattern, and accompanying symptoms. A threatened miscarriage involves mild vaginal bleeding with or without abdominal cramping, and many threatened miscarriages resolve without pregnancy loss. The bleeding may come and go over days or weeks.
When a miscarriage is progressing, the bleeding typically becomes heavier, bright red, and more sustained. You may notice tissue or clots passing, along with moderate to severe pelvic and lower abdominal pain. A complete miscarriage usually involves heavy bleeding and intense cramping. A missed miscarriage, by contrast, produces no bleeding or pain at all. The pregnancy stops developing but the tissue remains in the uterus, often discovered only during a routine ultrasound.
About 10 to 20% of known pregnancies end in miscarriage, most in the first trimester. Light spotting without heavy bleeding or significant pain is far more likely to be benign than to signal a loss.
Ectopic Pregnancy
An ectopic pregnancy occurs when a fertilized egg implants outside the uterus, most often in a fallopian tube. It affects roughly 7 to 8 out of every 1,000 pregnancies. The embryo cannot survive in this location, and as it grows, it can rupture the tube and cause life-threatening internal bleeding.
Vaginal bleeding is sometimes the only early sign. Other symptoms include sharp or stabbing pain on one side of the pelvis or abdomen, shoulder pain (caused by internal bleeding irritating the diaphragm), weakness, lightheadedness, or fainting. If you experience spotting alongside any of these symptoms, this is a medical emergency. Ectopic pregnancies are diagnosed with ultrasound and blood tests and require prompt treatment.
Molar Pregnancy
A molar pregnancy is rare, occurring in about 1 in 1,000 pregnancies. It happens when abnormal tissue grows in the uterus instead of a healthy embryo. Vaginal bleeding is a common symptom, sometimes accompanied by severe nausea and vomiting that goes beyond typical morning sickness. Blood tests show abnormally high levels of hCG, the pregnancy hormone, which can be a diagnostic clue. Molar pregnancies are usually detected on ultrasound and require medical treatment to remove the abnormal tissue.
How to Evaluate Your Spotting
Not all spotting carries the same weight. A few features can help you gauge what you’re dealing with:
- Color: Pink or brown spotting is more likely benign. Bright red bleeding that increases in volume is more concerning.
- Volume: Spotting that stays light enough to need only a panty liner is less worrying than bleeding that soaks through a pad.
- Duration: Spotting that resolves within a day or two, especially after sex or an exam, is usually harmless. Bleeding that persists or worsens needs evaluation.
- Pain: Mild, occasional cramping is normal in early pregnancy. Sharp, one-sided, or severe pain alongside bleeding raises the concern for ectopic pregnancy or miscarriage.
- Other symptoms: Dizziness, fainting, fever, or foul-smelling discharge alongside bleeding all warrant prompt medical attention.
ACOG recommends contacting your ob-gyn about any bleeding during pregnancy. In most cases, a provider can use ultrasound and blood work to quickly determine the cause and reassure you or begin appropriate care.