Vaginal bleeding during pregnancy is almost always a source of worry for a pregnant woman, but it’s not always a sign that something is wrong. Studies such as this one show that around 20% of pregnant women experience early bleeding, and little more than half of those pregnancies end in miscarriage. Even in this study, the number of pregnant women may have been underreported and therefore, the true number of women who have bled in early pregnancy is not known. However, it is a common occurrence, which must be investigated by your practitioner when it happens.
Less Serious Causes
One of the most common reasons for bleeding early in pregnancy is implantation. Implantation bleeding occurs around two weeks after conception and is the result of the fertilized egg burrowing into the endometrial lining. Sometimes this bleeding is mistaken for a normal period, so a woman may not realize she is pregnant until the following month. Those women who are Rh-negative should be very cognizant of this fact because what is believed to be a late normal period, actually may be a miscarriage in disguise and can cause problems for subsequent pregnancies with respect to alloimmunization. Please refer to my health book, “Inside Information for Women” for more on Rh-alloimmunization.
Other causes of bleeding during pregnancy that do not indicate harm to the fetus can include a cervix that is more sensitive and tender than usual, which can lead to bleeding, especially after intercourse. However, there is no way to know for sure what is causing your bleeding without an examination, so bleeding during pregnancy should always be evaluated by your doctor.
More Serious Causes
Ectopic pregnancy is another reason for bleeding early in pregnancy. These are pregnancies that implant in the fallopian tubes or other location outside the uterus. This type of bleeding may be accompanied by pain, either sharp pain or cramping, and lower-than-normal levels of hCG, or there may be no pain at all, that is, until it ruptures. Women who have had ectopic pregnancies before, pelvic surgery, or infection in the fallopian tubes are more likely to experience an ectopic pregnancy in a subsequent pregnancy. Untreated, an ectopic pregnancy can result in a ruptured fallopian tube, causing massive hemorrhage and may lead to death of the patient.
A miscarriage, which is the lay term for a spontaneous abortion, will also cause bleeding, and unfortunately, cannot usually be prevented or stopped. Most miscarriages occur during the first trimester (the first 12 weeks of gestation), and may cause vaginal bleeding, cramping, and the passage of tissue through the vagina. A miscarriage, while heartbreaking in many instances, is not a sign that the mother did anything wrong, nor is it a sign that future pregnancies are likely to end in miscarriage.
Bleeding in the second half of pregnancy is more likely than earlier bleeding to be caused by something serious. These causes can include placental abruption, or placenta previa. In placental abruption, the normally-implanted placenta separates from the uterine wall prematurely, such as after a motor vehicle accident or after a fall or other blunt trauma. In placenta previa, the abnormally-implanted placenta is positioned too low in the uterus, partially or completely covering the cervix. Any bleeding during pregnancy requires immediate attention in order to properly diagnose and treat the condition.
Again, to emphasize the importance of bleeding during pregnancy, let me reiterate: Any bleeding during pregnancy warrants an immediate call to your doctor to rule out serious causes or take appropriate measures to treat them.
– Yvonne S. Thornton, M. D., M. P. H