Spontaneous miscarriages are losses before the 20th week of gestation (pregnancy). It is the loss occurs before 10 weeks we consider the pregnancy to be developmentally an embryo. If the loss is after 10 weeks and before 20 weeks, it is termed “fetus.” Regardless of the developmental stage, a loss is a loss. The joyous thoughts and feelings (and sometimes nausea) attributed to pregnancy can dissolve in an instant.
There are risk factors associated with recurrent pregnancy loss. They include advanced maternal age, previous losses and smoking exposure. Advanced maternal age suggests that the oocytes are impaired from the onset. We know that at 40, for instance 60-70% of the oocytes are abnormal. In the case of abnormal oocyte-fertilization, it may be that the embryo realizes it is affected and stops growth. Alternatively, perhaps the maternal side quenches embryo growth realizing this pregnancy will never be. Regardless, the result is the same and loss and associated feelings ensue.
Additionally, it is possible that losses may stem from an impaired endometrium. Alterations in the expression of genes associated with implantation may impair implantation and/or progression of the developing embryo. The endometrial receptivity assay (ERA) may afford us insight into these losses.
Past obstetric history is important and influences outcome, regardless of the source of loss. For instance, the risk of loss in future pregnancy is 20% after one loss, 28% after two consecutive losses and increases to approximately 40% after 3 consecutive losses. In women who have had a successful pregnancy, the loss rate is less than 10%.
Social influences are exactly that. Smoking has the greatest bias promoting loss. It is unclear if it is related to the toxic chemicals ingested in the smoke, or the effects of the nicotine, such as vasoconstriction. Other factors, in excess have negative effects. This cast of characters are the usuals: excess alcohol, caffeine and any illicit drugs.
There is much of the narrative in spontaneous miscarriages that cannot be controlled. Is it nature correcting and redirecting or an embryo with potential squelched by other influences.
If you have questions about pregnancy loss, please contact us. We are here to help.