Bleeding during pregnancy is relatively common, but it can be a dangerous sign.

Visit your doctor even if its spotting or it stops.

What causes bleeding early in pregnancy?

• Having sex- mostly due to pregnancy changes in cervix
• An infection
• Smoking
• Implantation Bleeding- When a fertilized egg (embryo) attaches to the lining of the uterus (womb) and begins to grow. Usually occur 10-14days after conception. It is harmless.
• Invasive testing like Amniocentesis and Chorionic villus sampling- done to check genetic abnormalities.
• Hormone changes.
• Medical conditions- Bleeding disorders
• Changes in your cervix.

Occasionally bleeding or spotting in the first trimester can be due to a serious problem, like:

• Miscarriage- loss of pregnancy before 20weeks. Almost all women who miscarry have bleeding or spotting before the miscarriage. Bleeding can be along with pain abdomen.
• Ectopic pregnancy-fertilized egg implants outside uterine cavity and begins to grow. 
• Molar pregnancy- it is growth of abnormal tissue in the uterus, instead of a baby. Molar pregnancy is rare.

What causes bleeding in the Second and Third Trimesters?

Abnormal bleeding in late pregnancy is considered more serious because it can lead to severe complications to mother or baby. 

• Placenta previa-the placenta is located in lower uterine segment, partially or completely covers the internal OS. Placenta previa is not very common in the late third trimester, occurs in one in 200 pregnancies. It leads to painless bleeding.
• Placental abruption- In about 1% of pregnancies, the placenta separates its attachment on the uterus before or during labour. Placental abruption is very dangerous for the mother and baby both. It is often associated with severe abdominal pain, severe bleeding from the vagina, tender uterus, and backache.
• Uterine rupture-In rare cases, a scar from a previous C-section or uterine surgery can tear open during pregnancy. Uterine rupture can be life-threatening, and requires an emergency C-section. It can present with pain and tenderness in the abdomen.
• Vasa previa- In rare circumstances, baby’s blood vessels in the umbilical cord or placenta lies just above the opening to the birth canal. It can be fatal for the baby because the blood vessels can tear anytime, causing the baby to bleed severely and lose oxygen. It might be associated with abnormal fetal heart rate and excessive bleeding.
• Premature labor- Vaginal bleeding late in pregnancy can be due to your body getting ready to deliver. Preterm labour is when labour starts before 37th week of pregnancy. Other symptoms of preterm labor include contractions, vaginal discharge, abdominal pressure, and lower backache.

Other causes of bleeding in late pregnancy are:

• Sex
• Internal examination by your doctor.
• SHOW- Mucus plug which was inside cervix during pregnancy comes out, as the cervix is getting ready for labour to start. It can happen anytime from few days before contractions start or during labour itself.
• Injury to the cervix or vagina
• Polyps- usually painless bleeding
•  Cancer

What should you do if you have bleeding or spotting during pregnancy?

Seeking medical attention immediately is must in case of-

• Heavy bleeding
• Bleeding with pain or cramping
• Dizziness and bleeding
• Pain in your belly or pelvis
• Passing some tissue with blood

Keep a record of amount of bleeding, if it gets heavier or lighter, and number of pads you are using. 

Check the color of the blood.  Your provider may want to know. Bleeding can be brown, dark or bright red.

Do not use a tampon, douche or have sex during bleeding.

Inform your Doctor if you are Rh Negative.

Diagnosis

To find out the cause of bleeding, you will need to have a detailed vaginal or pelvic examination, an ultrasound scan or hormonal levels through blood tests.

Your doctor will inquire about other symptoms, like as abdominal cramp, dizziness and pain. Sometimes it might not be possible to find out what caused the bleeding.

How are bleeding and spotting treated?

• Treatment depends on cause of the bleeding. 
• Rest is very important part of treatment during bleeding.
• Take time off from work and take rest for a little while.
• Don’t have sex, douche or use tampons.
• If your symptoms are not severe and you are preterm-you’ll be monitored and can be kept in hospital for observation.
• Severe Symptoms and term gestation can mandate delivery.