Miscarriage or habitual abortion or recurrent pregnancy loss could be the toughest phase in a women’s life. A pain that no one can understand. The pain generally converts into depression. In this article, we will look closely to understand the causes of recurrent miscarriage.

Recurrent Miscarriage or recurrent pregnancy loss is a term simply meaning occurrence of 3 consecutive pregnancy losses before 20 weeks or 24 weeks in some countries. The causes of recurrent miscarriage are complex and most often obscure. There may be many factors which are recurrent and non recurrent and sometimes there are unknown factors present responsible for early and late miscarriage.

Causes of miscarriage or Recurrent pregnancy loss

The causes of miscarriage are very complex and obscure. The following are potential causes.

Environmental factors

Conclusions relating to environmental factors are difficult to prove.

  • Smoking-Increases the risks of miscarriage due to decreased oxygen transfer to the fetus.
  • Alcohol consumption should be avoided during pregnancy.
  • X-rays and anti-cancerous drugs are known to cause miscarriage.
  • Contraceptive Agents like IUD  increases the risk known to cause recurrent miscarriage.
  • Drugs, chemicals, Anesthetic gases, arsenic, aniline, lead, formaldehyde cause miscarriage.
  • Unexplained causes
  • Increasing maternal age can affect the function of ovaries.

In spite of many causes mentioned it is difficult to pinpoint the exact cause of miscarriage.

Endocrine and metabolic factors

  • Luteal phase defect (L.P.D): It results in early miscarriage as implantation and placentation are not supported properly.
  • Deficient progesterone secretion: The cause is deficient progesterone secretion from corpus-luteum or poor endometrial response to the progesterone hormone.
  • Thyroid abnormalities: Overt hypothyroidism or hyperthyroidism is associated with increased fetal loss.
  • Thyroid and Diabetes mellitus when uncontrolled can cause miscarriages.

Blood group incompatibility

Incompatible ABO group mating may be responsible for early pregnancy wastage and often recurrent but Rh incompatibility is a rare cause of death of the fetus before 28 weeks. Couple with group ‘A’ husband and group ‘O’ wife have higher incidence of abortion.

Immunological disorders

Both Autoimmune and Alloimmune factors can cause miscarriage.

Autoimmune disease: Can cause miscarriage usually in second trimester. These patients can form antibodies against their own tissues and placenta. These antibodies ultimately can cause rejection of early pregnancy.

Alloimmune disease: Paternal antigens which are foreign to the mother invoke a protective blocking antibody response.

These blocking antibodies can prevent maternal immune cells from recognizing the fetus as a foreign entity.

Genetic factors 

Most of the early miscarriages are due to chromosomal abnormality.

  • Polyploidy has been the cause in about 22% of miscarriage cases.
  • Monosomy constitutes 20% of all miscarriage cases. In Monosomy the commonest is Monosomy x.
  • Autosomal trisomy is commonest cytogenic abnormality.
  • Structural chromosomal rearrangements are present in 2-4% of the miscarriages.

These include translocation, deletion, inversion and ring formation.

Other chromosomal abnormalities are also present like mosaic, double trisomy in about 4% of the cases.

Anatomical abnormalities

  • Cervico-Uterine causes-These are related to mostly second trimester abortions.
  • Cervical incompetence, either congenital or acquired is one of the most common causes of recurrent abortion.
  • Congenital malfunction of the uterus  may be responsible.
  • Reduce intra-uterine volume, increased expensile property of uterus. Reduced vascularity of placenta when implanted on septum.
  • Increased uterine irritability and contraction.
  • Uterine fibroid may also be responsible for infertility and abortion.
  • Intra-uterine adhesion interfere with implantation, placenta and fetal growth.


Infections can cause late as well as early abortions. Miscarriage due to infection are quite rare in developed countries, but continues to grow in under developed countries. Trans-placental fetal infections occur with most micro organisms and fetal losses could be caused by any infection like:

  • Viral-Rubella, Cytomegalo, Variola or HIV can cause infection.
  • Parasitic: Toxoplasma, malaria.
  • Bacterial: Bacterial infections like Chlamydia, Brucella can cause abortion before 20th week because of effective thickness of placental barrier.

What to do when miscarriage happens

The process of expulsion of fetus is like that of mini labor. The fetus is expelled out first followed by expulsion of placenta after a varying interval. Follow these steps right away after 2nd recurrent pregnancy loss or miscarriage.

Recurrent pregnancy loss test

New studies have shown that the couple should consider recurrent pregnancy loss test after two consecutive pregnancy loss. Women in their late 30's have more chances of recurrent pregnancy loss. There are many tests to rule out the cause of recurrent pregnancy loss, so consult your Doctor for detailed information.

Support programs or support groups

One can seek help from the various support programs or groups, developed for women suffering from recurrent pregnancy losses, available locally at the gynecology and obstetrics hospitals and clinics or on the internet.