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Spontaneous miscarriages, usually occurring during the 1st trimester of pregnancy (up to and including the 13th week), are a common complication and refer to the ‘spontaneous (without intervention) loss of the pregnancy (embryo/fetus) before the stage of viability (24th week)’.

They are classified as threatened, incomplete, complete, missed, etc. The causes are multifactorial and in the majority of cases remain unknown (>50%).

They evidently result from a complex interaction between parental age and genetic, immunological, hormonal and environmental factors.

The reported frequency varies considerably among different studies, mainly due to differences in methodology and the recording of outcomes.

Overall, among women of reproductive age (15-45 years), it is estimated that 10-15% of clinically diagnosed pregnancies result in spontaneous miscarriage. However, many more pregnancies are lost before they are clinically diagnosed, usually by transvaginal ultrasound. It is estimated that ultimately only 30% of all conceptions result in the birth of a live child.

These percentages vary widely and increase steadily with advancing age. For example, while before the age of 30 they do not exceed 10% of all pregnancies, at the age of 45 and over they exceed 50%! Women with a previous history of miscarriage show a tendency toward recurrence; it is estimated that, without treatment, after two miscarriages the risk doubles and after three it quadruples!

Interestingly, according to recent research, this predisposition in women also increases significantly in those who experienced other types of complications in a previous pregnancy, such as preterm birth, Cesarean section, gestational diabetes, low birth weight of the pregnant woman herself, etc.!

In view of the above associations between miscarriages and various obstetric complications in a previous pregnancy, the existence of a common pathological background is suspected, a possibility that requires further investigation and is already the subject of ongoing research.

In light of these new observations that have recently emerged, women with a similar history may henceforth require additional monitoring and management.

Another predictive indicator of increased risk, regardless of age, is considered to be declining ovarian function (ovarian reserve), based on AMH (Anti-Müllerian Hormone) levels.

Recent studies also indicate that obesity increases the risk of both sporadic and recurrent spontaneous miscarriages. In couples with recurrent 1st-trimester miscarriages, in approximately 2-5% of cases one of the two partners is a carrier of a balanced structural chromosomal abnormality, usually a balanced reciprocal or Robertsonian translocation.

Male age and the risk of miscarriage.

In recent decades, the age of marriage and childbearing has been steadily increasing for both women and men, with the result that they quite often resort to time-consuming and costly methods due to the progressive decline in their reproductive capacity, particularly after the age of 35.

Couples should be informed about the additional risks associated with both motherhood and fatherhood at an advanced age. It has been statistically demonstrated that male age over 50 is an independent factor associated with an increased risk of miscarriage. This is a point that is often overlooked.

In addition, according to recent studies, it has been suggested that advanced paternal reproductive age (>40) may be associated with an increased risk of obstetric complications and health problems in the newborn, such as a small increase in the risk of rare anatomical abnormalities (of the skull, limbs and heart), autism, intellectual disorders (including earlier onset of symptoms of schizophrenia later in life), acute lymphoblastic leukemia, etc., possibly due to mutations that occur more frequently in older men.

However, this field of research remains relatively limited, with conflicting results.

The risk of these complications is considered small and remains disputed, particularly in comparison with the risks associated with advanced maternal age, and requires further investigation. Nevertheless, seeking genetic counseling when a man of advanced reproductive age (>40) is planning a pregnancy is not without merit.

Spontaneous miscarriage, meaning pregnancy loss despite the couple’s desire to continue the pregnancy, is generally accompanied by a high emotional burden, particularly when it recurs or when it follows a prolonged attempt to conceive due to infertility.

These couples require psychological support and genetic counseling.

Conclusion

• Spontaneous miscarriage is a common pregnancy complication with a tendency to recur.

• It is directly associated with maternal age and, to a lesser extent, paternal age.

• A common pathological background with other pregnancy complications is suspected.