Recurrent Miscarriage

Causes of Recurrent Miscarriage

There are many causes of miscarriage in general and for couples with recurrent miscarriage these factors also apply.  One of the most important factors relating to miscarriage is the age of a woman who becomes pregnant, since we know that egg age is important to the developing baby.  These risks are as follows:

Should a couple have a miscarriage, then there is an increased risk of miscarriage in the next pregnancy – this is increased as the number of miscarriages increases and investigations are necessary to look for reversible causes.  At this time, there is no good scientific evidence that cigarette smoking or caffeine consumption increases the risk of miscarriage, however we recommend no smoking or drinking during pregnancy for other associated risks to your pregnancy and for your own health and limiting caffeine intake.  There is science to link alcohol to recurrent miscarriage and this should definitely be avoided if you have had this problem with early pregnancy.

There are a variety of uncommon conditions that may contribute to recurrent miscarriage.  Recognising these is important, since their treatment may reduce the risk of a subsequent pregnancy loss.  Antiphospholipid Syndrome occurs when the body make antibodies that directly affect the implanting embryo or developing fetus.  These antibodies are found in approximately 15% of women with recurrent miscarriage and its recognition is important since this may be treatable and without any treatments, success rates for pregnancy are less than 10%.  Other immune factors have also been studied, including the finding of abnormal numbers of natural killer (NK) cells found in the lining of the uterus (the endometrium) and in the blood in women with recurrent miscarriage. This research is still controversial and therefore this test is not routinely offered in the first line of investigations.

The chromosomal make-up of parents is also important since abnormalities of the chromosomal pattern may be responsible for up to 60% of miscarriage in any situation.  In a smaller number of couples, there is a situation called a balanced chromosomal abnormality.  This is where all of the genetic information is present in both the male and female partners, but may be in a mixed up pattern in one of them.  This means that when an embryo is being made with half the information from each parent, this mixed-up genetic information means that proper development of a baby is not possible and this results in a miscarriage.

Structural abnormalities of the uterus and cervix have been found to be factors in recurrent miscarriage for some couples.  If there is a developmental abnormality such as an unusual uterine shape or reduced amount of tissue in the cervix, then this may cause recurrent miscarriage.  In addition, infections, injury to the uterus or the cervix and any resulting scar tissue could contribute to ongoing problems.  Maternal diseases such as diabetes or those that affect blood clotting are also factors that may be associated with recurrent miscarriage and these should be sought and treated of present.

Although specific causes for recurrent miscarriage are sought, it is important to note that 50% of couples with this problem have no apparent cause for their recurrent miscarriage.  Although this may be frustrating, this is associated with a better outcome than when a specific cause is found in many circumstances, so this should not always be seen in a negative way.