When you and your husband decided to start trying for a baby, you never imagined you would run into any problems, or that it would take you long to conceive. Although you did indeed conceive within a few months, you ended up losing the pregnancy a few weeks later. After deciding to try again, the same thing happened once more. You and your partner are both healthy, so what on earth could be wrong?

There are many causes of recurrent miscarriage, and one may occur even if both you and your partner are young and healthy. One of the causes behind this problem is infections - both bacterial and viral.

Although it would take a very persistent bug to cause recurrent miscarriages, it’s important that we explore the possibilities, so you can feel informed.

So, let’s start with outlining some of the viral infections which may cause recurrent miscarriages:

Cytomegalovirus infection in pregnancy

Cytomegalovirus (CMV) is one of the herpes group of viruses, and can be caught by close physical contact or by infected blood, urine, or secretions of breast milk and saliva. This is an infection that often goes unrecognised. Around 50% of women in countries like the UK have never had a CMV infection.

In pregnancy, 1% (1 in 200) of women will catch their first CMV infection, and amongst these infected cases, the virus will pass to the fetus 40% of the time. In the UK, a diagnosis of a CMV infection isn’t considered a reason to end a pregnancy.

Human Immunodeficiency Virus (HIV)

Human Immunodeficiency Virus (HIV) can be passed to a baby in utero. The current treatment for women is to take antiretroviral (ARVs) drugs throughout their pregnancy. If a woman is on regular ARVs and is carefully monitored (with their viral load remaining low), they can safely deliver vaginally. However, for mothers with a persistently high viral load, delivery by elective Caesarean section is thought to be the best way to protect the baby from obtaining the virus.

Now that we’ve looked at some of the viral infections that can cause recurrent miscarriages, let’s look at the bacteria and other micro-organisms that could have the same effect:

Syphilis

Syphilis is spread by sexual contact, and is a proven infectious cause of recurrent miscarriage. In the past, it has been referred to as ‘la plus grande avorteuse’ in French - translating to ‘the great abortionist’. However, it is also relatively rare in developed countries, as all pregnant women are screened for it. Nevertheless, it is still important to continue to look for this organism amongst all pregnant women, as in the last decade there has been an increase in infections. If a woman with Syphilis becomes infected during the first trimester, the risk of miscarriage is lower.

Streptococcus B

1 in 10 women have streptococcus B present in their vagina during their pregnancy. This is a bug that happens to grow well in amniotic fluid, and is rather resistant to the acid environment of the vagina. If the pregnant woman experiences a premature rupture of the membranes, then this bug can infect the premature baby. If this bug is suspected at any point during the pregnancy, it is important that vaginal swabs and a urine sample are taken to look for it.

Mycoplasma and ureaplasma

Mycoplasma and ureaplasma are very common organisms found in the vagina or cervix in 70% of all women who are sexually active. They can be identified by vaginal and cervical swabs during the first trimester of pregnancy. Because they are so common, they have been sighted as a cause of sporadic miscarriage. However, some studies have suggested that this might not be completely accurate.

Bacterial vaginosis

Bacterial vaginosis (BV) is a vaginal infection where the normal vaginal organisms are replaced by anaerobic bacteria. This infection can cause preterm labour, and is also considered to be the cause of some later miscarriages, at about 20 weeks of gestation. Although there are opinions on why this may be, one explanation cites that BV causes endometriosis (inflammation of the womb lining) which can affect implantation and early embryo development.

Future developments

We know that infection may lead to miscarriage. However, the medical field is working on the ability to assess a woman’s risk of miscarriage, understand the underlying causes of pregnancy loss, and predict responses to new treatments.

What are the infectious causes behind recurrent miscarriage?

Unii looks at a heartbreaking subject for any parent-to-be.