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Vaginal Bleeding & Spotting in Early Pregnancy

While most pregnancies will be smooth with few complications, up to 1 in 5 (20%) pregnant women experience some spotting or vaginal bleeding during the 1st trimester of pregnancy (a.k.a. early pregnancy).

First trimester vaginal bleeding is defined as vaginal bleeding during the first 12 weeks of pregnancy.

In early pregnancy, you may experience some light vaginal bleeding when your developing embryo implants itself in the womb (a.k.a. implantation bleeding). This kind of vaginal bleeding is completely harmless and often happens around the time when your first period after conception would have been due.

If you are NOT pregnant and having vaginal bleeding, please refer to my other article abnormal vaginal bleeding.

5 Causes of Vaginal Bleeding & Spotting in Early Pregnancy
1) Miscarriage

Miscarriage occurs when the pregnancy ends before the 24th week of pregnancy and are relatively common. Up to 1 in 5 pregnancies ends in a miscarriage during the first trimester.

Common symptoms of miscarriage include vaginal bleeding and abdominal pain. However, some missed carriages may have no symptoms.

Miscarriages can be further categorized as threatened, complete, incomplete or missed and also further classified as sporadic or recurrent (>3 miscarriages).

Threatened Miscarriage
Incomplete Miscarriage
Complete Miscarriage
Missed Miscarriage
There are several risk factors for miscarriage:
Endocrine Disorder
Maternal Age

Other less common risk factors include occupational chemical exposure or radiation exposure.

2) Ectopic Pregnancy

Ectopic pregnancy occurs when a fertilized egg implants outside the womb – for instance in the fallopian tube, ovary, etc. This can cause vaginal bleeding but is more commonly associated with abdominal pain.

All pregnant women with vaginal bleeding with or without abdominal pain should have an ultrasound scan performed to identify the location of the pregnancy. Early diagnosis of ectopic pregnancy is key to preserving fertility, and preventing complications, some which can be fatal.

diagram of ectopic pregnancy

An ectopic pregnancy is when a fertilized egg implants in the fallopian tube instead of the uterus or womb.

Risk factors for ectopic pregnancy
  1. Having a copper or hormonal intrauterine device (IUD)
  2. Previous history of ectopic pregnancy
  3. History of genital tract infection, including pelvic inflammatory disease, Chlamydia, gonorrhoea, etc.
  4. Previous history of any fallopian tube surgery
  5. Current pregnancy conceived via In vitro fertilization (IVF)
  6. Smoking
3) Local Causes: Cervical polyps, Cervical cancer

The majority of cervical polyps are non-cancerous or benign, and are common during pregnancy.

Most of the time they do not cause any symptoms or problems and it’s likely that you wouldn’t even notice if you had one.

However. occasionally these polyps can start to bleed on their own or through physical contact such as during sex. Usually, polyps will get smaller and resolve after delivery and surgery is not needed during pregnancy unless there is constant bleeding or significant symptoms of discomfort.

Vaginal bleeding is rarely caused by changes in the cervical cells (i.e. pre-cancerous to cancerous changes). If this is suspected during examination, a pap smear test may be performed. In most cases this should not affect your pregnancy and can be delayed until after the birth.

cervical polyp in ultrasound scan

A cervical polyp as seen on an ultrasound scan. Credit: Wikipedia

4) Bleeding After Sex

During pregnancy, the cervix softens and the blood supply to the cervix increases. As a result, sexual intercourse can cause light bleeding ranging from a few hours to several days after sex.

However, you should always inform your doctor if you experience any bleeding during pregnancy as the episode of bleeding may be unrelated to the cervical changes.

5) Unexplained Bleeding (in a Normal Pregnancy)

In about 1/3 of pregnant women, the cause of vaginal bleeding is unknown. In these cases, all investigations including ultrasound scans appear normal and the baby appears healthy and is developing well.

The bleeding may or may not happen again during the pregnancy but if you start to bleed again, it is advisable to see your doctor for an evaluation.

In summary, if you are pregnant and you are experiencing any vaginal bleeding with or without abdominal pain, I would strongly advise you to see a doctor for further evaluation.

Some preconception advice to help reduce the risk of miscarriage or ectopic pregnancy include:

doctor with stethoscope
  • To have a pap smear test performed before getting pregnant as it would make it easier for the doctor attending you to know your updated pap smear status.
  • Screen for any sexually transmitted infection (STI) especially if you are at risk of any before getting pregnant.

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About Dr. Sim Li Kun

Dr Sim Li Kun graduated from the University of Bristol, UK in 2009 where she has worked for 2 years before moving to Singapore. Currently she is practicing in a private medical group, Dr Tan & partners, in Singapore which has a special interest in men's and women's health, as well as tackling HIV and the spread of STDs.

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