What causes sudden menstrual-like bleeding at 13 weeks of pregnancy, and what should be done?

Nov 14, 2025 Source: Cainiu Health

Dr. Zhang Lu

Introduction

Menstruation usually refers to a woman's monthly period. In general, sudden bleeding resembling menstruation at 13 weeks of pregnancy may be caused by cervical ectropion, excessive fatigue, threatened miscarriage, cervical polyps, abnormal placental position, or other reasons. It is recommended to seek medical attention promptly, identify the underlying cause, and receive appropriate treatment under a doctor's guidance. In daily life, wear loose clothing and avoid putting pressure on the abdomen.

Menstruation usually refers to a woman's monthly period. In general, vaginal bleeding resembling menstruation at 13 weeks of pregnancy may be caused by cervical ectropion, excessive fatigue, threatened miscarriage, cervical polyps, abnormal placental position, or other reasons. It is recommended to seek medical attention promptly, identify the underlying cause, and receive appropriate treatment under a doctor's guidance. Specific causes are analyzed as follows:

1. Cervical ectropion: Hormonal changes during pregnancy can cause the cervical columnar epithelium to shift outward, making the cervical surface fragile. Even minor stimulation may lead to bleeding, which typically does not involve abdominal pain. Avoid strenuous exercise and sexual intercourse; clean the external genital area daily with warm water, keep it dry, and follow medical advice for regular follow-up visits.

2. Excessive fatigue: Long-term sleep deprivation or heavy physical labor can exhaust the body and affect uterine stability, leading to light bleeding. Immediately rest in bed, ensure 8–9 hours of sleep per day, avoid sudden movements when getting up, and increase nutritional intake such as eggs and lean meat to relieve physical fatigue.

3. Threatened miscarriage: Abnormal embryonic development or insufficient hormone levels may trigger uterine contractions, resulting in bleeding accompanied by abdominal pain. Follow your doctor’s instructions to use medications such as progesterone capsules, dydrogesterone tablets, or human chorionic gonadotropin injections to support the pregnancy. Strict bed rest is required, and emotional fluctuations should be avoided.

4. Cervical polyps: Polyps formed by overgrowth of cervical mucosa may become engorged and rupture easily during pregnancy, causing heavy menstrual-like bleeding. A cervical polyp removal procedure is needed. The surgery is quick and minimally invasive. After the procedure, follow medical advice to take antibiotics such as cefixime dispersible tablets, amoxicillin capsules, or metronidazole tablets to prevent infection.

5. Abnormal placental position: Low-lying placenta or placenta previa that covers the cervix may cause bleeding when stretched. This condition often occurs without abdominal pain but carries high risks. Immediate hospitalization and monitoring are necessary. When resting in bed, adopt a left lateral position, avoid straining during bowel movements, and if needed, consider early delivery via cesarean section to ensure maternal and fetal safety.

In daily life, wear loose clothing to avoid abdominal pressure. Maintain emotional stability and avoid anxiety. Eat a light, easily digestible diet to prevent constipation. Attend regular prenatal checkups to closely monitor fetal development and your own health status.

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What causes slight bleeding at 13 weeks of pregnancy?

In general, slight bleeding at 13 weeks of pregnancy may be related to hormonal changes, low-lying placenta, vaginitis, threatened miscarriage, cervical polyps, or other causes. It is recommended that patients promptly go to the hospital and follow medical advice for treatment. In daily life, pregnant women should maintain a balanced diet, appropriately consume vitamins and protein, ensure adequate rest, and avoid excessive fatigue.

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Is the fetus stable at 13 weeks of pregnancy?

Under normal circumstances, the fetus is relatively stable at 13 weeks of gestation, and the risk of miscarriage has significantly decreased compared to the early stages of pregnancy. However, it has not yet reached a completely safe stage, so continued prenatal precautions are necessary. At 13 weeks pregnant, maintain a regular sleep schedule, avoid staying up late and heavy physical labor, and engage in mild exercises such as walking. Pay attention to balanced nutrition in your diet, and increase intake of high-quality protein and foods rich in folic acid.

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Why do I keep tossing and turning during sleep at 13 weeks pregnant, and what should I do about it?

At 13 weeks of pregnancy, frequent tossing and turning during sleep may be caused by discomfort from uterine enlargement, hormonal changes, prenatal anxiety, leg cramps during pregnancy, gastroesophageal reflux, and other factors. These symptoms can be improved by adjusting sleeping positions, improving diet, or using medications. If symptoms persist or are accompanied by severe discomfort, prompt medical attention is necessary. The gradually enlarging uterus may compress surrounding tissues.

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Is it normal for placental maturity to be grade 0 at 13 weeks of pregnancy?

Placental maturity grade 0 at 13 weeks of gestation is generally normal. At this stage, the placenta is in its initial developmental phase, functioning well and highly active, capable of providing sufficient nutrients and oxygen to the fetus. Typically, placental maturity remains at grade 0 before 28 weeks of pregnancy, so there is usually no need for excessive concern. However, if prenatal examinations reveal an abnormally increased placental maturity grade or other abnormal indicators, further evaluation may be necessary.