Monogenic disorders frequently involve point mutations. This single nucleotide exchange makes the analysis of point mutations more complex as stringent assays need to be established that permit a clear distinction between normal and mutant alleles. The prenatal diagnosis of this multitude of hereditary genetic disorders currently relies on invasive procedures,¹ such as amniocentesis or chorionic villous sampling, which are associated with a small but significant risk of fetal loss.^2,3 To avoid this procedure-related risk, several strategies have been considered for noninvasive assessment of fetal genetic traits, including the isolation of rare fetal cells from the maternal circulation and the analysis of circulatory fetal DNA in maternal plasma.^1,4-6

To investigate whether the transfer of fetal blood cells to the maternal circulation is perturbed in pregnancies affected by preeclampsia. Fetal erythroblasts were isolated from eight women with clinically diagnosed preeclampsia (blood pressure values of at least 140/90 mmHg and associated proteinuria) and an equal number of matched corresponding controls. All patients in both groups were pregnant with male singleton fetuses. The presence of fetal cells was evaluated histologically and by fluorescence in situ hybridization for X and Y chromosomes. The number of fetal cells was higher in preeclamptic patients than in controls, with respect to both nucleated red blood cells (median per 200 cells 38 versus 7; P < .001) and the proportion of these cells that were of fetal origin (median per 2000 cells 9 versus 2; P = .001). These results suggest that the trafficking of fetal cells into the maternal periphery is disturbed in patients with preeclampsia. Because it is unlikely that such an altered flow of cells is restricted to the erythroblasts examined in this study, these findings also may lead to interesting new concepts regarding the development of preeclampsia and possibly the associated syndrome of hemolysis, elevated liver enzymes, and low platelets.

To determine if carbon dioxide laser conization of the cervix is a risk factor for preterm delivery in subsequent gestations and to evaluate whether there is any relationship between cone height and duration of pregnancy. Patients of fertile age who had carbon dioxide laser conization were followed for reproductive events. Cases were matched one-to-one with controls for known risk factors for preterm delivery. Pregnancy duration, rate of preterm birth, and mode of delivery were studied. Parametric and nonparametric tests were used for statistical analysis. Logistic regression analysis and Cox proportional hazard modeling were used to investigate the relationship between cone height and subsequent preterm delivery. Sixty-four women with singleton pregnancies after carbon dioxide laser conization and 64 controls were included in the study. Overall, no difference was found in the rate of preterm delivery and duration of pregnancy. However, women with cone height of at least 10 mm had a higher rate of preterm delivery than either those with cone height less than 10 mm (five of 23 versus one of 41, P = .01) or the controls (five of 23 versus three of 64, P < .05). Cone height of at least 10 mm remained significant in predicting the occurrence of preterm delivery and the duration of pregnancy after adjusting for known risk factors (odds ratio 11.1, P < .05). Cone height of at least 10 mm is an independent risk factor for the duration of pregnancy and for the occurrence of preterm delivery in the subsequent gestation.