Bleeding During Pregnancy: Not a Period—When to Worry

True menstrual periods do not occur during pregnancy. Any vaginal bleeding in pregnancy warrants medical evaluation to determine the cause and ensure maternal-fetal safety.

Common Causes by Trimester

First Trimester

• Implantation bleeding: Light spotting 6–12 days post-conception.
• Subchorionic hematoma: Blood collection between chorion and uterine wall; often resolves.
• Cervical changes: Friable cervix bleeds after exam or intercourse.
• Early pregnancy loss (miscarriage): Bleeding + cramping; ~10–20% of known pregnancies.
• Ectopic pregnancy: Pain + bleeding; life-threatening if ruptured.
• Molar pregnancy: Abnormal placental growth; rare.

Second/Third Trimester

• Placenta previa: Painless bright red bleeding; placenta covers os.
• Placental abruption: Painful dark bleeding + uterine tenderness; emergency.
• Vasa previa: Fetal vessels cross cervical os; rupture → fetal hemorrhage.
• Preterm labor: Bloody show + contractions.
• Cervical insufficiency: Painless dilation + bleeding.

Action Steps

1. Call your OB/GYN or midwife immediately. Describe amount (spotting vs. soaking pads), color, clots, pain, contractions.
2. Do not use tampons (infection risk, obscures amount).
3. Save any passed tissue for possible pathology.
4. Go to ER if: Heavy bleeding (soaking >1 pad/hour), severe pain, dizziness, fever, or decreased fetal movement.

Many causes are benign, but only a provider can distinguish them. Never assume bleeding is "just a period."