A true menstrual period, involving the shedding of the uterine lining, cannot occur during pregnancy. This shedding happens when a fertilized egg doesn’t implant and hormone levels decline. Pregnancy causes hormonal shifts that prevent this process. Therefore, any bleeding during pregnancy is a symptom requiring attention, not a period.
Bleeding is Not a Period
The physiological changes in a pregnant body actively prevent menstruation. After conception, human chorionic gonadotropin (hCG) signals the ovaries to produce progesterone. Progesterone maintains the uterine lining, thickening it to support the embryo and preventing shedding contractions. This hormonal environment also suppresses ovulation. Thus, any blood loss during pregnancy is bleeding from the uterus or cervix, not a menstrual cycle.
Types of Bleeding During Pregnancy
Bleeding during pregnancy offers initial clues about its nature. Spotting is very light bleeding (a few drops, pink, red, or brown) that typically doesn’t require a pad. Light bleeding is more substantial than spotting but less than a typical menstrual flow, usually requiring a panty liner or light pad.
Heavy bleeding is comparable to or more profuse than a typical period. It often soaks pads quickly, appearing bright red and potentially containing blood clots. While visual characteristics offer clues, they don’t definitively diagnose the cause.
Causes of Bleeding During Pregnancy
First trimester bleeding (first 12 weeks) has several potential origins.
Implantation Bleeding
Implantation bleeding, light spotting (pink or brown) around 6-12 days post-conception, occurs when the fertilized egg attaches.
Cervical Changes
Increased blood flow makes the cervix more sensitive, causing light spotting after intercourse or pelvic exams.
Subchorionic Hematoma
A common subchorionic hematoma involves blood accumulating between the chorion and uterine wall, resulting in bleeding from light spotting to heavy flow.
Miscarriage
Miscarriage, pregnancy loss before 20 weeks, is a common cause of early bleeding, often with cramping. Bleeding varies from light spotting to heavy flow with clots.
Ectopic Pregnancy
An ectopic pregnancy, where the fertilized egg implants outside the uterus (often in a fallopian tube), can cause light spotting or heavy bleeding with severe abdominal pain.
Molar Pregnancy
Molar pregnancy, a rare condition involving abnormal growth of placental tissue, can cause heavy, dark red bleeding.
Bleeding in the second and third trimesters (from week 13) can indicate more serious issues.
Placenta Previa
Placenta previa occurs when the placenta partially or completely covers the cervix, often causing painless, heavy, bright red bleeding.
Placental Abruption
Placental abruption involves premature detachment of the placenta from the uterine wall, leading to sudden, heavy, dark red bleeding with severe abdominal pain.
Preterm Labor
Preterm labor (before 37 weeks) can manifest with light spotting to heavy bleeding, often alongside contractions.
Vasa Previa
Vasa previa, a rare condition, involves fetal blood vessels crossing the cervical opening, causing painless, heavy, bright red bleeding.
When to Contact Your Doctor
Any bleeding during pregnancy, however light, warrants a call to a healthcare provider. Seek immediate medical attention for:
- Heavy bleeding soaking more than one pad per hour.
- Severe abdominal pain or cramping accompanying bleeding.
- Passing tissue or large blood clots.
- Dizziness, fainting, or weakness with bleeding.
- Fever or chills with bleeding.
Even light, persistent spotting should be reported to your medical professional for monitoring.
What to Expect at the Doctor’s Office
When experiencing bleeding during pregnancy, a healthcare provider will typically take a detailed medical history, including information about the bleeding’s characteristics and any accompanying symptoms. They will then perform:
- A physical examination, which may include a pelvic exam, to assess the source and amount of bleeding.
- An ultrasound to check for fetal heartbeat, determine pregnancy location, and assess placental position.
- Blood tests to measure hormone levels (e.g., hCG), blood type, and complete blood count.
- Urine tests to rule out infections or other issues.
Following these evaluations, the healthcare provider will discuss potential diagnoses and outline a management plan. This might involve watchful waiting, activity restrictions, medication, or, in more severe situations, hospitalization. Adhering to medical advice is important for managing any bleeding during pregnancy.