Is it normal to bleed during pregnancy?

Bleeding or spotting is quite common during pregnancy, occurring in 1 out of every 10 women during the first trimester [1]. In most cases, it results from the normal body changes taking place in pregnancy. It is important to know the types and reasons of bleeding so you would know when to worry about it while carrying.

Is light bleeding an early sign of pregnancy?

Light vaginal spotting is one of the earliest signs of pregnancy, along with nausea, bloating and abdominal cramping [2].

Vaginal bleeding vs. vaginal spotting

Although any bloody vaginal discharge in pregnancy is referred to as bleeding, vaginal bleeding and spotting have certain differences. Knowing the difference between the two is vital in order to understand the causes of the symptoms as well as to recognize any danger signs.

Spotting is when you occasionally notice just a little blood in your underwear. Counted among the harmless pregnancy signs, spotting is more common in the first trimester [3]. Bleeding, on the other hand, is having a heavy, menstrual-like flow which requires the use of pads or liners. It is often associated with abnormal conditions and complications [4]. It is advisable to contact your doctor if you experience any kind of bloody discharge [5], with or without pain and any other symptom as you cannot determine the causes and risks yourself.

What causes bleeding during pregnancy?

Bleeding can result from a number of causes with some of them being harmless [6] while others might signify life threatening conditions, both for the mother and child [7].

Normal causes of spotting in the first trimester

  • Implantation bleeding: Also known as streaking, it occurs in the third or fourth week of pregnancy, usually around the same time the next period is due [1]. The light spotting starts after the fertilized egg gets attached to the uterine wall, continuing for no longer than a couple of days. The hCG (human chorionic gonadotrophin) levels become high enough to be detected by a home pregnancy test about 5-6 days after the implantation bleeding [8].
  • Breakthrough bleeding: Another harmless cause of spotting, breakthrough bleeding occurs when you experience normal menstrual cycles even in pregnancy. Sometimes, the pregnancy hormone levels are not high enough to cover up the menstrual cycle and the symptoms associated with it (e.g. abdominal and lower back cramps, pelvic discomfort) [9]. However, breakthrough bleeding is characterized by light spotting as opposed to the regular heavy menstrual bleeding.
  • Bleeding or spotting after intercourse: Softening of the cervix, due to the pregnancy hormones, along with a raw spot referred to as cervical erosion is often responsible for light brown spotting after sex in early as well as later pregnancy [10]. This type of spotting can also result from some cervical/vaginal infection or certain harmless growths (polyp).
  • Carrying twins: Spotting is more common in twin pregnancies due to the higher pregnancy hormone levels [11].

Serious causes of bleeding in early pregnancy

  • Miscarriage: A miscarriage can occur any time in a pregnancy, with its chances being highest during the first trimester [12]. It is one of the principal causes of bleeding in the first 12 weeks [13].
  • Chemical pregnancy: It refers to a very early miscarriage, taking place even before the fertilized egg can attach itself to the uterus. This type of miscarriage occurs within the first month of pregnancy with its primary symptom being vaginal bleeding or spotting [14].
  • Ectopic pregnancy (tubal pregnancy): Another principal cause of bleeding, it occurs when the embryo implants itself anywhere other than the uterine cavity [15].
  • Molar pregnancy: An abnormal fertilization of the egg causes clusters of water-filled sacs grow within the womb [16], leading to considerable vaginal bleeding.
  • Subchorionic bleeding or hematoma: Characterized by a blood accumulation between the uterine wall and placenta or within the placenta itself [17], subchorionic hematoma can eventually lead to placental abruption in some cases. However, it often remains asymptomatic apart from slight spotting, healing itself over time [18].
  • Decidual Tissues: Sometimes, small pieces of tissue gets detached and disintegrated due to some unknown reason, causing light spotting. It is sometimes referred to as a “threatened miscarriage”, but does not usually cause any serious harm to the fetus [19].

Other causes may include uterine fibroids, endometritis and a low lying or bicornuate (heart-shaped) uterus. All these cases require proper medical attention to have a healthy pregnancy and baby. Taking anti-nausea medicines like Zofran is often associated with complications like bleeding and miscarriage.

Causes of bleeding in the second and third trimesters

Bleeding in the second and third trimesters is not as common as it is in early pregnancy. The symptom is often associated with some complication in these later stages. However, a pinkish light spotting with mucous-like discharge near full-term (37th week) can signify the starting of labor [20]. Any pressure applied on the uterus or cervix during an internal medical exam can also lead to mild spotting [21].  Other, more serious causes of heavy bleeding after the 15th week include:

  • Placenta previa: Sometimes, the placenta partially or completely blocks the cervical opening while some placental blood vessels stretch and rupture, resulting in bleeding [22].
  • Placental abruption: Refers to the condition where the peeling off of the placenta from the uterine wall leads to bleeding [21].
  • Uterine rupture: Bleeding occurs due to a breakage or rupture in the uterine wall [23].
  • Vasa Previa: A rare cause of bleeding, where the umbilical cord gets attached to the uterine wall, causing the fetal blood vessels to pass into the birth canal [24].
  • Cervical Abnormalities: Other probable causes include inflamed cervix, cervical infection, premature opening of cervix (that leads to premature labor) and certain cervical growths [20].

Tips for bleeding or spotting while pregnant

Here are a few guidelines to reduce the risks of complications and help the assessment until your doctor can diagnose the responsible factors:

  • Drinking lots of water to prevent dehydration and keeping pregnancy symptoms, like constipation, in check
  • Bed rest
  • Keeping your feet elevated when sitting or lying [3]
  • Avoiding walking, climbing stairs and lifting any heavy objects
  • Avoiding exercise and intercourse [25]
  • Keeping track of the amount of bleeding to find out if it is increasing
  • Recording the type of bleeding, meaning whether it is dark red, pinkish or brown and if there are any blood clots [7] (bright red blood is more often a serious cause of concern than brownish spotting)
  • Practicing stress relief techniques like yoga

When to call the doctor?

  • Experiencing constant bleeding (even if in small amounts) for over 24 hours at any stage of pregnancy [26]
  • Vaginal bleeding and passing tissues along with intense abdominal cramping and lower back pain (might indicate a miscarriage)
  • Considerable bleeding accompanied by abdominal pain, fever (over 100.5°F) and chills [7]
  • Recurring light vaginal bleeding (in the second trimester) that goes away on its own within a couple of hours
  • Heavy period-like bleeding with abdominal and pelvic pain, nausea and vomiting (might indicate an ectopic pregnancy) [3]
  • Unexplained bleeding accompanied by dizziness, fainting and a racing heart (might indicate low blood pressure) [27]
  • Vaginal bleeding along with fever, nausea, pain during intercourse or lower abdominal pain (might indicate sexually transmitted diseases like chlamydia, gonorrhea or other conditions like UTI and kidney infection) [28]

Tests and exams

Your doctor will carry out a number of routine diagnostic tests to find out the possible factors responsible for the problem. A vaginal examination may be necessary to determine whether you have an infection, while an ultrasound scan can help to check for an ectopic pregnancy or miscarriage [29]. Routine blood and urine tests can determine your pregnancy hormone levels. Another blood test may be ordered to check the blood group and Rh status [30].

Women with high risk pregnancies might need special medication to ascertain healthy fetal growth while those with ectopic pregnancies require surgery [30]. Rh-negative mothers might be given a shot of rhesus immune globulin to save the pregnancy until further testing [31].