Is Superfertility Associated with Recurrent Pregnancy Loss?
A recent hypothesis has implicated superfertility as a cause of recurrent pregnancy loss. Clinical support for the concept comes from one report that 40% of women experiencing recurrent miscarriages had monthly fecundity rates of 60% or greater and thus were designated as superfertile.
Methods of study
To confirm or refute this finding, clinical histories of 201 women with a history of recurrent pregnancy loss were reviewed and months to desired pregnancy, karyotypes of their products of conception as well as results of laboratory tests including antiphospholipid antibodies and circulating natural killer cells were recorded.
The prevalence of superfertility was 32% (64/201) among recurrently aborting women compared with 3% of the general population according to the model of Tietze (P < 0.0001). Fifty-nine of the 201 (30%) study patients displayed presence of APA,LA, increased CD56+ cells, or increased NK cytotoxicity and were designated as having an immunologic risk factor. Of the 192 karyotypes of products of conception from women with a history of recurrent miscarriage, 153 (80%) had a normal chromosome complement and 38 (20%) were abnormal. Among the normal karyotypes, 86 (56%) were 46XX and 67 (44%) were 46XY.
Recurrent pregnancy loss is associated with superfertility in 32%, immunologic risk factors in 30% and a 20% frequency of chromosomally abnormal pregnancy losses. Thus, implantation failure can result from too much or too little implantation.