What Are the Causes of Bleeding During Pregnancy?

Maybe you have just begun your pregnancy journey, entering the first trimester with excitement and joy. Or perhaps you have progressed into your second or third trimester, anxiously awaiting the moment when your baby will be in your arms. And then one day the bleeding begins. Depending on the stage of your pregnancy, the causes for bleeding during pregnancy can range from miscarriage to early labor.


The American Pregnancy Association notes that when bleeding occurs in the first half of the pregnancy, miscarriage is a possible cause. A miscarriage is the body’s way of coping with a pregnancy that is not developing in a healthy way, though while 15 to 20 percent of all pregnancies end in miscarriage, it is not an indication that the mother herself is unhealthy and will not prevent healthy pregnancies in the future.

Aside from vaginal bleeding, other symptoms you may experience include cramping in the lower stomach that’s more severe than menstrual cramps, and the passing of vaginal tissue.

Changes in the Cervix

Changes in the cervix typically include a softening of, or an increased blood flow to, the cervix. The Mayo Clinic explains that these typically occur during the first trimester, result in harmless vaginal bleeding and occur after a pelvic exam or sexual intercourse.

Ectopic Pregnancy

Ectopic pregnancies occur when the fertilized egg implants, or attaches itself, to an area outside of the uterus such as the fallopian tubes. This results in bleeding as the egg continues to grow and develop without the proper space to do it in.

While not as common as a miscarriage, ectopic pregnancies occur in one out of 60 pregnancies, according to the American Pregnancy Association. Common symptoms include cramping that’s stronger than menstrual cramps in the lower area of the stomach, sharp abdominal pains and vaginal bleeding.

Those at greatest risk include women with an infection in their fallopian tubes, women with a history of pelvic surgery and women with a history of ectopic pregnancies.

Placenta Previa

A serious medical condition requiring immediate medical attention, placenta previa occurs when the placenta either lies low or completely covers the cervix. The National Institutes of Health state that this condition happens in one out of 200 pregnancies, and is more prevalent in women with an abnormally developed uterus, women pregnant with multiples (twins, triplets, etc.) and women with large placentas.

The main symptom is sudden, painless vaginal bleeding occurring near the end of the second trimester or the beginning of the third. In certain situations, the bleeding may be severe and stop, but then begin again weeks later.

Preterm Labor

The American Pregnancy Association explains that the mucus plug may pass a few weeks before labor actually begins. This plug is a combination of small amounts of both mucus and blood.

Preterm labor is different, though–it is labor beginning prior to 37 weeks of pregnancy, and its symptoms include vaginal discharge including water, blood and mucus; low, dull back pain; regular contractions or a tightening of the uterus, and stomach cramps that may or may not be accompanied by diarrhea.

About this Author

Based in Jamestown, Pa., Hannah Rice Myers has more than 10 years of experience as a freelance writer, specializing in the health industry. Many of her articles have appeared in newspapers, as well as “Curing Epilepsy: Hope Through Research.” Rice received her master’s degree in nursing from Upstate Medical University in 2001.