Vaginal bleeding during pregnancy is a common occurrence. Up to 25% of pregnancies experience some bleeding, particularly in the first trimester. While alarming, it does not always indicate a serious problem. Understanding its causes can help pregnant individuals navigate this experience.
Understanding Vaginal Bleeding During Pregnancy
Vaginal bleeding during pregnancy can manifest in different ways, from light spotting to a heavier flow. Spotting involves a few drops of blood, not enough to saturate a pad, appearing only when wiping. Bleeding requires a pad to contain the flow.
Blood color can vary, from light pink to bright red or dark red/brown. Light pink or brownish discharge suggests older or less active bleeding, while bright red indicates fresh bleeding.
Bleeding is more prevalent in the first trimester. Any vaginal bleeding during pregnancy warrants consultation with a healthcare provider to determine its cause.
Common Causes of Bleeding by Trimester
The causes of vaginal bleeding often differ by trimester. Understanding these reasons provides insight into potential origins.
Implantation Bleeding
Implantation bleeding occurs when a fertilized egg attaches to the uterine lining, typically 10 to 14 days after conception. It presents as light, pink or brownish spotting lasting one to three days, sometimes mistaken for a light period.
Cervical Irritation
Cervical irritation is another common cause, as the cervix becomes more sensitive and vascular during pregnancy. Bleeding can happen after sexual intercourse or a pelvic examination.
Subchorionic Hematoma
A subchorionic hematoma is a collection of blood between the uterine wall and the chorionic membrane. Frequent in early pregnancy, it can cause bleeding from light spotting to a heavy flow, sometimes with mild cramping. Many resolve spontaneously without complications.
Miscarriage
Miscarriage, the loss of a pregnancy before 20 weeks, is a cause of first-trimester bleeding. Vaginal bleeding with cramping is a common sign, and bleeding can be heavy with blood clots. Approximately 50% of pregnancies with first-trimester bleeding ultimately result in miscarriage.
In a threatened miscarriage, bleeding occurs, but the cervix remains closed, and the pregnancy may continue. An inevitable miscarriage occurs when the cervix opens and bleeding persists. An incomplete miscarriage involves passing some pregnancy tissue.
A complete miscarriage means all tissue has been expelled. A missed miscarriage refers to fetal death without immediate expulsion of tissue.
Cervical Insufficiency
Cervical insufficiency occurs when the cervix begins to open too early in the pregnancy without contractions, potentially leading to preterm birth or late miscarriage.
Placenta Previa
Placenta previa, where the placenta partially or completely covers the cervix, can be diagnosed in the second trimester. It often presents as painless, bright red vaginal bleeding. As the uterus grows, the placenta may appear to move away from the cervix, resolving the condition.
Placental Abruption
Placental abruption, the premature separation of the placenta from the uterine lining, can occur after 20 weeks. It is more prevalent in the third trimester. Symptoms include vaginal bleeding, abdominal pain, uterine tenderness, and contractions. External bleeding does not always reflect the abruption’s severity.
Late Miscarriage
Late miscarriage, pregnancy loss between 13 and 20 weeks, also presents with vaginal bleeding, strong cramping, and sometimes a gush of fluid.
In the third trimester, bleeding causes often relate to placental issues or the onset of labor.
Placental Issues (Placenta Previa and Abruption)
Placenta previa remains a concern, causing painless, bright red bleeding. Placental abruption is more common in this trimester, characterized by painful, dark red bleeding, abdominal pain, and uterine contractions.
Preterm Labor
Preterm labor, occurring before 37 weeks, can also be associated with bleeding, contractions, cramping, or membrane rupture.
Bloody Show
A “bloody show” is a normal sign of labor preparation, involving light bleeding mixed with mucus. It occurs as the cervix thins and dilates, dislodging the mucus plug and tearing small blood vessels. The discharge can be pink, brown, or red and may appear days before labor.
Vasa Previa
Vasa previa is a rare but severe condition where fetal blood vessels run unprotected across or near the cervix. If these vessels rupture, it can lead to life-threatening blood loss for the baby.
When to Seek Immediate Medical Care
Contacting a healthcare provider is recommended for any vaginal bleeding experienced during pregnancy. Certain symptoms indicate immediate medical attention is needed for the well-being of both the pregnant individual and the baby.
Seek prompt care for heavy bleeding, such as soaking through multiple pads per hour or passing large blood clots. Severe or persistent cramping or abdominal pain also warrants immediate evaluation.
Other concerning signs include passing any tissue from the vagina, or experiencing dizziness or fainting. A fever or chills with bleeding also prompt urgent medical consultation.
Any persistent bleeding or bleeding with pain requires prompt assessment. In later pregnancy, a noticeable reduction in fetal movement alongside bleeding requires immediate attention.
Medical Evaluation and Next Steps
A thorough evaluation identifies the cause of vaginal bleeding during pregnancy. This often begins with a physical examination, including a speculum exam, to assess the cervix and determine the bleeding source.
An ultrasound is a standard diagnostic tool. It confirms pregnancy viability, locates its position (ruling out ectopic pregnancy), assesses placental location, and checks for conditions like subchorionic hematomas. A transvaginal ultrasound provides clearer, more precise imaging.
Blood tests are also part of the evaluation. Human chorionic gonadotropin (hCG) levels monitor pregnancy progression. Blood type and Rh factor are determined, as Rh-negative individuals may require Rh immune globulin if bleeding occurs. A complete blood count helps assess the extent of blood loss.
Management strategies vary based on diagnosis. They can range from watchful waiting and activity modification, such as pelvic rest or reduced strenuous activity, to medication. In more severe situations, hospitalization or other interventions may be necessary. Adhering to medical advice is important for the best possible outcome.