| Reproductive Failure: Causal Factors |
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The World Health Organisation (WHO) defines spontaneous abortion as “(approximately equal to 20-22 weeks of gestation) or another product of gestation of any weight and specifically designated (e.g. hydatidiform mole) irrespective of gestational age and whether or not there is evidence of life” (WHO, 1976). Approximately 25% of pregnant women will threaten miscarriage, but a smaller percentage actually completes it. Most spontaneous abortions occur in the first trimester, with the median between 8 and 9 weeks of gestation. If a fetal heart is detected in the first trimester (5-14 weeks); 95-98% gestate successfully. Most of those who abort show either absent fetal heart or an empty gestational sac. Thus most pregnancy failures begin as fetus failure; this event precedes the development of symptoms and the initial events ultimately leading to miscarriage may occur within the first 5 weeks of gestation.
Numerous causes are identifiable for the occurrence of recurrent miscarriages (blighted ovum, chemical pregnancy, early miscarriage, failed IVF cycle, missed abortion, spontaneous abortion) which can be classified under immunological and non-immunological causes. Immunological causes comprise of any malfunctioning of the immune system which in turn recognizes the semi-allograft fetus to be foreign. Commonly, the following immunological factors can cause malfunctioning of the mother’s immune system:
- Natural killer cells,
- Cytokoine estimation,
- Antinuclear antibodies (ANA),
- Follicular fluid environment,
- Reynaud’s disease,
- Regulatory T cells,
- Activated T cells,
- Dendritic cells and macrophages
Non-immunological causes include chromosomal aberrations, endocrinological or anatomical aetiologies, exposure to toxic substances, thrombosis, previous IVF failures, poor egg quality, endometriosis, uterine abnormalities, male factors, and last but not the least emotional & physical stress. In our laboratory, we address the issue of recurrent miscarriages through immune evaluation of the patient as well as through cytogenetic testing. |
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