Bleeding in Pregnancy: Causes, and When It Is an Emergency

Bleeding occurs in roughly 20–30% of pregnancies during the first trimester and, in the majority of cases, does not prevent the pregnancy from progressing to a healthy outcome. However, not every bleed carries the same meaning: some represent a normal physiological process, while others may be the first sign of an emergency that requires prompt intervention. This guide reviews the causes of bleeding at different stages of pregnancy, which can be observed, and which are urgent.

Causes of bleeding in the first trimester (weeks 0–13)

1. Implantation bleeding

Occurs as the fertilised egg implants into the uterine wall, approximately 10–14 days after conception. It appears as light pink or brown spotting, lasts 1–3 days, is lighter than a menstrual period, and does not contain clots. It is painless or associated with a mild pulling sensation.

2. Threatened miscarriage (abortus imminens)

There is bleeding, but the cervix is closed and the pregnancy is still viable. This is one of the most frequent causes of first-trimester bleeding. When fetal cardiac activity is seen on ultrasound, the likelihood of the pregnancy continuing is high. Rest, avoidance of intercourse, and — where indicated — progesterone support may be recommended.

3. Early miscarriage (spontaneous abortion)

Roughly 10–15% of clinically recognised pregnancies end in miscarriage in the first trimester; the majority are caused by chromosomal abnormalities. Signs include progressively heavier bleeding, passage of clots or tissue, cramping abdominal pain, and a sudden decrease in pregnancy symptoms.

4. Ectopic pregnancy

Implantation of the fertilised egg outside the uterus — most often in a fallopian tube. It occurs in approximately 1–2% of pregnancies and is a life-threatening emergency. Symptoms include severe one-sided abdominal pain, bleeding, shoulder-tip pain, and dizziness. After 6 weeks, a positive pregnancy test with no intrauterine gestational sac on ultrasound is a strong warning sign.

5. Molar pregnancy (hydatidiform mole)

A rare abnormal development of the placenta. Diagnosis is based on bleeding, severe nausea and vomiting, markedly elevated hCG levels, and the typical "snowstorm" appearance on ultrasound. Treatment is uterine evacuation, followed by hCG monitoring.

6. Cervical causes

The vascularity of the cervix increases during pregnancy; contact bleeding may occur after intercourse, an examination, or from a cervical polyp. It is usually light, bright-red, and painless.

Causes of bleeding in the second and third trimesters (weeks 14–40)

1. Placenta praevia

The placenta partially or completely covers the internal cervical os. The classical presentation is sudden, painless, bright-red bleeding. It typically presents after 20 weeks and is diagnosed by ultrasound. Bleeding may require caesarean delivery.

2. Placental abruption (abruptio placentae)

Premature separation of the placenta from the uterine wall before delivery. It presents with severe abdominal pain, a board-like uterus, and dark bleeding. Occasionally the bleeding is concealed and shock develops without visible loss. It is a life-threatening emergency requiring urgent delivery for both mother and baby.

3. Vasa praevia

Fetal blood vessels run across the internal cervical os. Bleeding after rupture of the membranes is extremely dangerous for the baby and requires emergency caesarean delivery.

4. Preterm labour

Regular contractions and cervical dilatation before 37 weeks may be accompanied by a pinkish, mucus-tinged discharge known as the "show". Immediate assessment is essential and tocolytic therapy may be indicated.

5. Bloody show

The mucus, pink or brown discharge that occurs as the cervix begins to soften and dilate near term. At 37 weeks or more it is physiological and signals that labour is approaching.

Situations requiring immediate hospital attention

What to do — and not to do — before your visit

Do

• Use a sanitary pad; note how often you need to change it to estimate the volume.
• If you pass tissue or clots, place them in a clean container and bring them to hospital.
• Record when the bleeding started, its colour (bright red, dark, brown), and any associated pain.
• If you are alone, inform a relative and arrange transport in advance.

Do not

• Do not use tampons; use pads only.
• Do not have intercourse.
• Do not perform a vaginal examination on yourself or douche.
• Do not take pain relievers, aspirin, or blood thinners without medical advice.

Rh incompatibility and bleeding

In Rh-negative mothers, every episode of bleeding should be assessed for the need for anti-D (Rh) immunoglobulin to prevent the development of antibodies against the fetus. An injection given within 72 hours protects future pregnancies.

Frequently asked questions

Is brown spotting dangerous?

Brown discharge indicates older blood (slowly draining over several days) and is usually less concerning than fresh bleeding. Any spotting during pregnancy should still be reported.

I bled after intercourse — is there a problem?

Because cervical vascularity is increased in pregnancy, contact bleeding is common and usually harmless. However, since the amount can vary and other causes may be present, any first-time episode should be evaluated.

I saw bleeding — does this mean I will miscarry?

No. The great majority of women who experience first-trimester bleeding go on to deliver healthy babies. When fetal cardiac activity is seen on ultrasound and the cervix is closed, the probability that the pregnancy will continue is high.

Does bed rest help during a bleeding episode?

There is no strong evidence that bed rest prevents miscarriage. However, avoiding heavy physical activity, travel, and intercourse while active bleeding continues is a reasonable precaution.

Assessment of pregnancy bleeding in Adana

Bleeding during pregnancy is understandably a source of anxiety for the mother and family. Early evaluation is essential — both to identify the underlying cause and to begin appropriate treatment on time. For early pregnancy ultrasound, evaluation of bleeding, anti-D administration, and comprehensive pregnancy care in Adana, you can contact Op. Dr. Sadık Kükrer.